SPOJ 刷题记录

按点赞数降序

297 二分

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 1e5 + ;

int a[N], c, n;

bool check(int d) {

    int pre = a[], cnt = ;

    for(int i = ; i <= n; i++) {

        if((a[i] - pre) >= d) {

            pre = a[i];

            cnt++;

        }

    }

    return cnt >= c;

}

int main() {

    int T;

    scanf("%d", &T);

    while(T--) {

        scanf("%d%d", &n, &c);

        for (int i = ; i <= n; i++) scanf("%d", &a[i]);

        sort(a+, a++n);

        int l = , r = 1e9+, m = (l+r) >> ;

        while(l < r) {

            if(check(m)) l = m;

            else r = m - ;

            m = (l+r+) >> ;

            //cout << l <<" " << r << endl;

        }

        printf("%d\n", m);

    }

    return ;

}

2 区间素数筛

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 1e5 + ;

bool notp_big[N], notp_small[N];

void prime(LL a, LL b) {

    mem(notp_big, false);

    if(a==) notp_big[] = true;

    for (LL i = ; i*i <= b; i++) {

        if(!notp_small[i]) {

            for (LL j = i+i; j*j <= b; j += i) notp_small[j] = true;

            for (LL j = max(2LL, (a+i-)/i)*i; j <= b; j += i)notp_big[j-a] = true;

        }

    }

}

int main() {

    int T, n, m;

    scanf("%d", &T);

    while(T--) {

        scanf("%d%d", &n, &m);

        prime(n, m);

        for (int i = n; i <= m; i++) if(!notp_big[i-n])printf("%d\n", i);

    }

    return ;

}

346 dp 小于5e6预处理，大于5e6递归

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 5e6+;

int dp[N];

map<int, LL>mp;

LL f(int n) {

    if(n <= 5e6) return dp[n];

    else if(mp[n] != ) return mp[n];

    return max((LL)n, f(n/)+f(n/)+f(n/));

}

int main() {

    int n;

    dp[]=;

    dp[]=;

    for (int i = ; i < N; i++) {

        dp[i] = max(i, dp[i/]+dp[i/]+dp[i/]);

    }

    while(~ scanf("%d", &n)) {

        mp.clear();

        printf("%lld\n", f(n));

    }

    return ;

}

394 dp 注意0的情况

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = ;

char s[N];

LL dp[N];

int main() {

    while(~scanf("%s", s+)) {

        //printf("%s\n", s+1);

        if(s[] == '')break;

        dp[] = dp[] = ;

        int n = strlen(s+);

        for (int i = ; i <= n; i++) {

            if(s[i-] != '') {

                int t = (s[i-]-'')* + s[i]-'';

                //cout << t << endl;

                if(t <= ) {

                    if(s[i] != '')dp[i] = dp[i-] + dp[i-];

                    else dp[i] = dp[i-];

                }

                else dp[i] = dp[i-];

            }

            else dp[i] = dp[i-];

        }

        printf("%lld\n", dp[n]);

    }

    return ;

}

1043 线段数区间合并，lv记录这段区间以左端点为起点的最大和，rv同理

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 5e4 + ;

const int INF = 0x7f7f7f7f;

struct Tree {

    int sum, lv, rv, ans;

}tree[N<<];

void push_up(int rt) {

    tree[rt].sum = tree[rt<<].sum + tree[rt<<|].sum;

    tree[rt].lv = max(tree[rt<<].lv, tree[rt<<].sum + tree[rt<<|].lv);

    tree[rt].rv = max(tree[rt<<|].rv, tree[rt<<|].sum + tree[rt<<].rv);

    tree[rt].ans = max(tree[rt<<].rv + tree[rt<<|].lv, max(tree[rt<<].ans, tree[rt<<|].ans));

}

void build(int rt, int l, int r) {

    if(l == r) {

        scanf("%d", &tree[rt].ans);

        tree[rt].lv = tree[rt].rv = tree[rt].sum = tree[rt].ans;

        return ;

    }

    int m = (l+r) >> ;

    build(ls);

    build(rs);

    push_up(rt);

}

Tree query(int L, int R, int rt, int l, int r) {

    if(L <= l && r <= R) return tree[rt];

    int m = (l + r) >> ;

    if(R <= m) return query(L, R, ls);

    else if(L > m) return query(L, R, rs);

    Tree lft = query(L, R, ls);

    Tree rit = query(L, R, rs);

    int sum = lft.sum+rit.sum;

    int lv = max(lft.lv, lft.sum+rit.lv);

    int rv = max(rit.rv, rit.sum+lft.rv);

    int ans = max(lft.rv+rit.lv, max(lft.ans, rit.ans));

    return Tree{sum, lv, rv, ans};

}

int main() {

    int n, m, x, y;

    scanf("%d", &n);

    build(, , n);

    scanf("%d", &m);

    while(m --) {

        scanf("%d%d", &x, &y);

        Tree res = query(x, y, , , n);

        printf("%d\n", res.ans);

    }

    return ;

}

6256 普通的逆序数，不过我使用了最近学的方法，从大到小加入位置，跑的比较优秀

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 2e5 + ;

pii a[N];

int bit[N], n;

void add(int x, int a) {

    while(x <= n) bit[x] += a, x += x&-x;

}

int query(int x) {

    int ans = ;

    while(x) ans += bit[x], x -= x&-x;

    return ans;

}

int main() {

    int T;

    scanf("%d", &T);

    while(T--) {

        scanf("%d", &n);

        for (int i = ; i <= n; i++) {

            scanf("%d", &a[i].fi);

            a[i].se = i;

        }

        sort(a+, a++n);

        mem(bit, );

        LL ans = ;

        for(int i = n; i >= ; i--) {

            ans += query(a[i].se);

            //cout <<".............."<< ans << endl;

            add(a[i].se, );

        }

        printf("%lld\n", ans);

    }

    return ;

}

5 纯暴力，从中间加

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 1e6 + ;

char s[N];

int num[N], t[N], n;

bool cmp() {

    for(int i = ;i <= n; i++) {

        if(t[i] < num[i]) return true;

        else if(t[i] > num[i]) return false;

    }

    return true;

}

int main() {

    int T;

    scanf("%d", &T);

    while(T--) {

        scanf("%s", s+);

        n = strlen(s+);

        for (int i = ; i <= n; i++) num[i] = s[i] - '';

        for (int i = ; i <= (n+)/; i++) {

            t[i] = t[n-i+] = num[i];

        }

        if(n==) {

            if(num[] == ) printf("11\n");

            else printf("%d\n", num[]+);

            continue;

        }

        while(cmp()) {

            t[(n+)/]++;

            for (int i = (n+)/; i >= ; i--) {

                t[i-] += t[i]/;

                t[i] %= ;

            }

            for (int i = ; i <= (n+)/; i++) {

                t[n-i+] = t[i];

            }

        }

        for (int i = ; i < n; i++) printf("%d", t[i]);

        if(t[n] == ) printf("1\n");//样例999

        else printf("%d\n", t[n]);

    }

    return ;

}

8002 树状数组区间更新，区间查询

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 1e5 + ;

int a[N], n;

LL sum[N], c1[N], c2[N];

void add(int x, int a) {

    LL t = x;

    while(x <= n) c1[x] += a, c2[x] += t*a, x += x&-x;

}

LL query(int x) {

    LL ans = ;

    LL t = x;

    while(x) ans += (t+) * c1[x] - c2[x], x -= x&-x;

    return ans;

}

int main() {

    int T, op, c, p, q, v;

    scanf("%d", &T);

    while(T--) {

        mem(c1, );

        mem(c2, );

        scanf("%d%d", &n, &c);

        while(c--) {

            scanf("%d", &op);

            if(op == ) {

                scanf("%d%d", &p, &q);

                printf("%lld\n", query(q) - query(p-));

            }

            else {

                scanf("%d%d%d", &p, &q, &v);

                add(p, v);

                add(q+, -v);

            }

        }

    }

    return ;

}

3267 离线+树状数组，每次保证这段区间每个数只更新一次，或者主席树(不会，等我学了在a)

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 3e5 + , M = 2e5 + ;

int a[N], nxt[N], bit[N], mp[M*], n;

struct node {

    int l, r, id;

    bool operator < (const node & t) const {

        if(l == t.l) return r < t.r;

        else return l < t.l;

    }

}Q[M];

int ans[N];

void add(int x, int a) {

    while(x <= n) bit[x] += a, x += x&-x;

}

int query(int x) {

    int ans = ;

    while(x) ans += bit[x], x -= x&-x;

    return ans;

}

int main() {

    int q;

    scanf("%d", &n);

    for (int i = ; i <= n; i++) scanf("%d", &a[i]);

    for (int i = ; i <= n; i++) {

        if(mp[a[i]] == ) {

            add(i, );

            mp[a[i]] = i;

        }

    }

    mem(mp, );

    for (int i = n; i; i--) {

        if(mp[a[i]] == ) {

            nxt[i] = n+;

            mp[a[i]] = i;

        }

        else {

            nxt[i] = mp[a[i]];

            mp[a[i]] = i;

        }

    }

    scanf("%d", &q);

    for (int i = ; i < q; i++) scanf("%d%d", &Q[i].l, &Q[i].r), Q[i].id = i;

    sort(Q, Q+q);

    int t = ;

    for (int i = ; i < q; i++) {

        while(t <= n && t < Q[i].l) add(nxt[t++], );

        ans[Q[i].id] = query(Q[i].r) - query(Q[i].l-);

    }

    for (int i = ; i < q; i++) printf("%d\n", ans[i]);

    return ;

}

主席树（2019.3更新），感觉这个没有离线优秀，不过思想还行，就当练练可持久化

#pragma GCC optimize(2)

#pragma GCC optimize(3)

#pragma GCC optimize(4)

#include<iostream>

#include<cstdio>

#include<vector>

#include<climits>

using namespace std;

#define y1 y11

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pli pair<LL, int>

#define pii pair<int, int>

#define piii pair<pii, int>

#define pdd pair<double, double>

#define mem(a, b) memset(a, b, sizeof(a))

#define debug(x) cerr << #x << " = " << x << "\n";

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

//head

const int N = 3e4 + , M = 1e6 + ;

int root[N], lson[M], rson[M], tree[M], tot = ;

void build(int &x, int l, int r) {

    x = ++tot;

    if(l == r) return ;

    int m = l+r >> ;

    build(lson[x], l, m);

    build(rson[x], m+, r);

    tree[x] = tree[lson[x]] + tree[rson[x]];

}

void update(int old, int &x, int p, int v, int l, int r) {

    x = ++tot;

    lson[x] = lson[old], rson[x] = rson[old], tree[x] = tree[old] + v;

    if(l == r) return ;

    int m = l+r >> ;

    if(p <= m) update(lson[x], lson[x], p, v, l, m);

    else update(rson[x], rson[x], p, v, m+, r);

}

int query(int L, int R, int x, int l, int r) {

    if(L <= l && r <= R) return tree[x];

    int m = l+r >> , ans = ;

    if(L <= m) ans += query(L, R, lson[x], l, m);

    if(R > m ) ans += query(L, R, rson[x], m+, r);

    return ans;

}

int n, a, mp[M], tmp, q, l, r;

int main() {

    scanf("%d", &n);

    build(root[], , n);

    for (int i = ; i <= n; ++i) {

        scanf("%d", &a);

        if(mp[a]) {

            update(root[i-], tmp, mp[a], -, , n);

            update(tmp, root[i], i, , , n);

        }

        else update(root[i-], root[i], i, , , n);

        mp[a] = i;

    }

    scanf("%d", &q);

    while(q--) {

        scanf("%d %d", &l, &r);

        printf("%d\n", query(l, r, root[r], , n));

    }

    return ;

}

1437 树的直径，两遍dfs

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 1e4 + ;

vector<int>g[N];

int mx = , ed = ;

void dfs(int o, int u, int st) {

    if(st > mx) {

        mx = st;

        ed = u;

    }

    for (int i = ; i < g[u].size(); i++) {

        if(g[u][i] != o) {

            dfs(u, g[u][i], st+);

        }

    }

}

int main() {

    int n, u, v;

    scanf("%d", &n);

    for (int i = ; i < n-; i++) {

        scanf("%d%d", &u, &v);

        g[u].pb(v);

        g[v].pb(u);

    }

    dfs(, , );

    dfs(, ed, );

    printf("%d\n", mx);

    return ;

}

1436 dfs

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 1e4 + ;

vector<int>g[N];

bool vis[N];

bool f = true;

void dfs(int o, int u) {

    vis[u] = true;

    for (int i = ; i < g[u].size(); i++) {

        if(g[u][i] != o) {

            if(!vis[g[u][i]])dfs(u, g[u][i]);

            else f = false;

        }

    }

}

int main() {

    int n, m, u, v;

    scanf("%d%d", &n, &m);

    for (int i = ; i < m; i++) {

        scanf("%d%d", &u, &v);

        g[u].pb(v);

        g[v].pb(u);

    }

    dfs(, );

    for (int i = ; i <= n; i++) if(!vis[i]) f = false;

    if(f) puts("YES");

    else puts("NO");

    return ;

}

6219 普通dp, 与LCS相似

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 2e3 + ;

char s[N], t[N];

int dp[N][N];

int main() {

    int T;

    scanf("%d", &T);

    while(T--) {

        scanf("%s", s+);

        scanf("%s", t+);

        int n = strlen(s+), m = strlen(t+);

        for (int i = ; i <= n; i++) {

            for (int j = ; j <= m; j++) {

                if(i||j){

                    if(i == ) dp[i][j] = j;

                    else if(j == ) dp[i][j] = i;

                    else if(s[i] == t[j]) dp[i][j] = dp[i-][j-];

                    else dp[i][j] = min(dp[i-][j-]+, min(dp[i-][j]+, dp[i][j-]+));

                }

            }

        }

        printf("%d\n", dp[n][m]);

    }

    return ;

}

3923 普通dp

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = ;

int a[N][N], dp[N][N];

int main() {

    int T, n, m;

    scanf("%d", &T);

    while(T--) {

        scanf("%d%d", &n, &m);

        for (int i = ; i <= n; i++) {

            for (int j = ; j <= m; j++) {

                scanf("%d", &a[i][j]);

            }

        }

        mem(dp, );

        for (int i = ; i <= m; i++) dp[][i] = a[][i];

        for (int i = ; i <= n; i++) {

            for (int j = ; j <= m; j++) {

                dp[i][j] = max(dp[i-][j], max(dp[i-][j-], dp[i-][j+])) + a[i][j];

            }

        }

        int ans = ;

        for (int i = ; i <= m; i++) ans = max(ans, dp[n][i]);

        printf("%d\n", ans);

    }

    return ;

}

95 栈模拟

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

stack<int>s;

int main() {

    int n, t;

    while(~scanf("%d", &n) && n) {

        while(!s.empty()) s.pop();

        int now = ;

        for (int i = ; i <= n; i++) {

            scanf("%d", &t);

            if(t == now) now++;

            else {

                s.push(t);

            }

            while(!s.empty() && s.top() == now) {

                s.pop();

                now++;

            }

        }

        //cout << now << endl;

        if(now == n+) puts("yes");

        else puts("no");

    }

    return ;

}

1021 原串与反串的LCS就是原串的最长回文子序列

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 6e3 + ;

char s[N], t[N];

int dp[N][N];

int main() {

    int T;

    scanf("%d", &T);

    while(T--) {

        scanf("%s", s+);

        int n = strlen(s+);

        for (int i = ; i <= n; i++) t[i] = s[n-i+];

        for (int i = ; i <= n; i++) {

            for (int j = ; j <= n; j++) {

                if(s[i] == t[j]) dp[i][j] = max(dp[i-][j-]+, max(dp[i-][j], dp[i][j-]));

                else dp[i][j] = max(dp[i-][j], dp[i][j-]);

            }

        }

        printf("%d\n", n-dp[n][n]);

    }

    return ;

}

14930 记忆化搜索

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 1e4 + ;

LL dp[N][];

int a[N], n;

LL dfs(int pos, int sta) {

    if(pos == n) {

        if(sta == ) return ;

        else return a[n];

    }

    if(~dp[pos][sta]) return dp[pos][sta];

    if(sta == ) return dp[pos][sta] = a[pos] + dfs(pos+, );

    else return dp[pos][sta] = max(dfs(pos+, ), dfs(pos+, ));

}

int main() {

    int T;

    scanf("%d", &T);

    for (int cs = ; cs <= T; cs++) {

        scanf("%d", &n);

        for (int i = ; i <= n; i++) scanf("%d", &a[i]);

        mem(dp, -);

        LL ans = max(dfs(, ), dfs(, ));

        printf("Case %d: %lld\n", cs, ans);

    }

    return ;

}

1841 bfs

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 1e4 + ;

bool notp[N];

bool vis[N];

int d[], dd[];

int p[] = {, , , , };

int a, b, ans;

bool bfs() {

    mem(vis, false);

    queue<pii>q;

    q.push(mp(a, ));

    vis[a] = true;

    while(!q.empty()) {

        pii p = q.front();

        q.pop();

        int t = p.fi;

        if(t == b) {

            ans = p.se;

            return true;

        }

        for (int i = ; i <= ; i++) {

            d[i] = t%;

            t /= ;

        }

        for (int i = ; i <= ; i++) {

            int t = ;

            if(i == ) t = ;

            for (int j = t; j < ; j++) {

                if(j == d[i]) continue;

                for (int k = ; k <= ; k++) {

                    if(k == i) continue;

                    dd[k] = d[k];

                }

                dd[i] = j;

                int n = ;

                for (int k = ; k >=; k--) n = n * + dd[k];

                if(!notp[n] && !vis[n]) {

                    vis[n] = true;

                    q.push(mp(n, p.se+));

                }

            }

        }

    }

    return false;

}

int main() {

    int T;

    scanf("%d", &T);

    for (int i = ; i < N; i++) {

        if(!notp[i]) {

            for (int j = i+i; j < N ;j += i) notp[j] = true;

        }

    }

    for (int cs = ; cs <= T; cs++) {

        scanf("%d%d", &a, &b);

        if(bfs())printf("%d\n", ans);

        else printf("Impossible\n");

    }

    return ;

}

97 背包dp

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = ;

int dp[N], c[N], v[N];

int main() {

    int n, m;

    while(~scanf("%d%d", &n, &m)) {

        if(!n && !m) return ;

        int ans;

        mem(dp, );

        for (int i = ; i <= m; i++) scanf("%d%d", &c[i], &v[i]);

        for (int i = ; i <= m; i++) {

            for (int j = n; j >= c[i]; j--) {

                dp[j] = max(dp[j-c[i]]+v[i], dp[j]);

            }

        }

        for (int i = n; i >= ; i--) if(dp[i] == dp[n]) ans = i;

        printf("%d %d\n", ans, dp[n]);

    }

    return ;

}

740 区间dp，小区间推大区间，dp[i][j] = max(dp[i+1][j] + (n+i-j) * a[i], dp[i][j-1] + (n+i-j) * a[j])

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 2e3 + ;

int dp[N][N], a[N];

int main() {

    int n;

    scanf("%d", &n);

    for (int i = ; i <= n; i++) scanf("%d", &a[i]);

    for (int i = n; i >=; i--) {

        dp[i][i] = a[i] * n;

        for (int j = i+; j <= n; j++) {

            dp[i][j] = max(dp[i+][j] + (n+i-j) * a[i], dp[i][j-] + (n+i-j) * a[j]);

        }

    }

    printf("%d\n", dp[][n]);

    return ;

}

206 每次向外扩展一次，做多扩展max(n,m)次，所以复杂度为max(n,m)*n*m

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = ;

const int INF = 0x3f3f3f3f;

char s[N][N];

int ans[N][N];

int dir[][] = {, , , , , -, -, };

int main() {

    int T, n, m;

    scanf("%d", &T);

    while(T--) {

        scanf("%d%d", &n, &m);

        mem(ans, INF);

        for (int i = ; i <= n; i++) scanf("%s", s[i]+);

        for (int i = ; i <= n; i++) {

            for (int j = ; j <= m; j++) {

                if(s[i][j] == '') ans[i][j] = ;

            }

        }

        for (int i = ; i <= max(n, m); i++) {

            for (int j = ; j <= n; j++) {

                for (int k = ; k <= m; k++) {

                    if(ans[j][k] != INF)

                    for (int l = ; l < ; l++) {

                        int x = j + dir[l][];

                        int y = k + dir[l][];

                        if( <= x && x <= n &&  <= y && y <= m) {

                            ans[x][y] = min(ans[x][y], ans[j][k] + );

                        }

                    }

                }

            }

        }

        for (int i = ; i <= n; i++) {

            for (int j = ; j <= m; j++) {

                printf("%d%c", ans[i][j], " \n"[j==m]);

            }

        }

    }

    return ;

}

9861 双指针

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 3e5 + ;

int a[N];

int main() {

    int n, m;

    scanf("%d%d", &n, &m);

    for (int i = ; i <= n; i++) {

        scanf("%d", &a[i]);

    }

    int ans = ;

    int l = , r = , sum = ;

    while(true) {

        while(sum <= m && r < n) {

            ans = max(ans, sum);

            sum += a[++r];

        }

        if(sum <= m) ans = max(ans, sum);

        while(sum > m) {

            sum -= a[++l];

        }

        if(sum <= m) ans = max(ans, sum);

        if(r == n) break;

    }

    printf("%d\n", ans);

    return ;

}

3377 带权并查集或普通并查集

带权

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 2e3 + ;

int fa[N], rnk[N];

void init(int n) {

    for (int i = ; i <= n; i++) {

        fa[i] = i;

        rnk[i] = ;

    }

}

int find(int x) {

    if(fa[x] == x) return x;

    else{

        int tmp = fa[x];

        fa[x] = find(fa[x]);

        rnk[x] = (rnk[x] + rnk[tmp]) % ;

        return fa[x];

    }

}

void merge(int x, int y) {

    int rx = find(x), ry = find(y);

    if(rx == ry) return;

    fa[rx] = ry;

    rnk[rx] = (rnk[y] +  -rnk[x]) % ;

}

int main() {

    int T, n, m, u, v;

    scanf("%d", &T);

    for (int cs = ; cs <= T; cs++) {

        scanf("%d%d", &n, &m);

        printf("Scenario #%d:\n", cs);

        init(n);

        bool f = false;

        for (int i = ; i < m; i++) {

            scanf("%d%d", &u, &v);

            if(find(u) == find(v) && rnk[u] == rnk[v]) f = true;

            else merge(u, v);

        }

        if(f) printf("Suspicious bugs found!\n");

        else printf("No suspicious bugs found!\n");

    }

    return ;

}

普通

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 2e3 + ;

int fa[N*];

void init(int n) {

    for (int i = ; i <= n*; i++) {

        fa[i] = i;

    }

}

int find(int x) {

    if(x == fa[x]) return x;

    else return fa[x] = find(fa[x]);

}

void merge(int x, int y) {

     int rx = find(x), ry = find(y);

     if(rx == ry) return;

     fa[rx] = ry;

}

int main() {

    int T, n, m, u, v;

    scanf("%d", &T);

    for (int cs = ; cs <= T; cs++) {

        scanf("%d%d", &n, &m);

        printf("Scenario #%d:\n", cs);

        init(n);

        bool f = false;

        for (int i = ; i < m; i++) {

            scanf("%d%d", &u, &v);

            if(find(u) == find(v) || find(u+n) == find(v+n)) f = true;

            else merge(u, v+n), merge(v, u+n);

        }

        if(f) printf("Suspicious bugs found!\n");

        else printf("No suspicious bugs found!\n");

    }

    return ;

}

10582 multiset维护（注意删一个元素需要s.erase(s.find(x)),否则会把所有的x都会删掉），顺便复习了一下st表，用st表写了一发

multiset

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 1e6 + ;

int a[N];

multiset<int>s;

int main() {

    int n, k;

    scanf("%d", &n);

    for (int i = ; i <= n; ++i) scanf("%d", &a[i]);

    scanf("%d", &k);

    for (int i = ; i < k; i++) s.insert(a[i]);

    for (int i = k; i <= n; i++) {

        s.insert(a[i]);

        auto it = s.end();

        it --;

        printf("%d%c", *it, " \n"[i==n]);

        s.erase(s.find(a[i-k+]));

    }

    return ;

}

st表

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 1e6 + ;

int a[N], st[N][];

int query(int l, int r) {

    int k = floor(log(r-l+)/log());

    return max(st[l][k], st[r - ( << k) + ][k]);

}

int main() {

    int n, k;

    scanf("%d", &n);

    for (int i = ; i <= n; ++i) scanf("%d", &a[i]);

    scanf("%d", &k);

    for (int i = n; i >= ; i--) {

        st[i][] = a[i];

        for (int j = ; j + ( << j-) <= n; j++) {

            st[i][j] = max(st[i][j-], st[i+( << j-)][j-]);

        }

    }

    for (int i = k; i <= n; i++) printf("%d%c", query(i-k+, i), " \n"[i==n]);

    return ;

}

4 stack

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 1e4 + ;

char s[N];

bool is(char c) {

    if(c == '+' || c == '-' || c == '*' || c == '/' || c == '^') return true;

    else return false;

}

int main() {

    int T;

    scanf("%d", &T);

    while(T--) {

        scanf("%s", s+);

        int n = strlen(s+);

        stack<char>st;

        for (int i = ; i <= n; i++) {

            if(isalpha(s[i])) putchar(s[i]);

            else if(is(s[i])) st.push(s[i]);

            else if(s[i] == ')') putchar(st.top()), st.pop();

        }

        puts("");

    }

    return ;

}

61 线段树区间合并，左区间的左括号和右区间的有括号抵消，看有没有剩下的没匹配的括号

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 3e4 + ;

char s[N];

struct  sg_tree{

    int L[N<<], R[N<<];

    void push_up(int rt) {

        L[rt] = L[rt<<] + L[rt<<|] - min(L[rt<<], R[rt<<|]);

        R[rt] = R[rt<<] + R[rt<<|] - min(L[rt<<], R[rt<<|]);

    }

    void build(int rt, int l,int r) {

        if(l == r) {

            if(s[l] == '(') L[rt] = , R[rt] = ;

            else R[rt] = , L[rt] = ;

            return ;

        }

        int m = (l+r) >> ;

        build(ls);

        build(rs);

        push_up(rt);

    }

    void update(int p, int rt, int l, int r) {

        if(l == r) {

            L[rt] ^= ;

            R[rt] ^= ;

            return ;

        }

        int m = (l+r) >> ;

        if(p <= m) update(p, ls);

        else update(p, rs);

        push_up(rt);

    }

}sg;

int main() {

    int n, m, t, cs = ;

    while(~ scanf("%d", &n)) {

        scanf("%s", s+);

        scanf("%d", &m);

        printf("Test %d:\n", ++cs);

        sg.build(, , n);

        while(m--) {

            scanf("%d", &t);

            if(!t) {

                if(sg.L[] || sg.R[]) printf("NO\n");

                else printf("YES\n");

            }

            else sg.update(t, , , n);

        }

    }

    return ;

}

1716 线段树区间合并，同1043

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 5e4 + ;

const int INF = 0x7f7f7f7f;

struct Tree {

    int sum, lv, rv, ans;

}tree[N<<];

void push_up(int rt) {

    tree[rt].sum = tree[rt<<].sum + tree[rt<<|].sum;

    tree[rt].lv = max(tree[rt<<].lv, tree[rt<<].sum + tree[rt<<|].lv);

    tree[rt].rv = max(tree[rt<<|].rv, tree[rt<<|].sum + tree[rt<<].rv);

    tree[rt].ans = max(tree[rt<<].rv + tree[rt<<|].lv, max(tree[rt<<].ans, tree[rt<<|].ans));

}

void build(int rt, int l, int r) {

    if(l == r) {

        scanf("%d", &tree[rt].ans);

        tree[rt].lv = tree[rt].rv = tree[rt].sum = tree[rt].ans;

        return ;

    }

    int m = (l+r) >> ;

    build(ls);

    build(rs);

    push_up(rt);

}

void update(int p, int x, int rt, int l ,int r) {

    if(l == r) {

        tree[rt].lv = tree[rt].rv = tree[rt].sum = tree[rt].ans = x;

        return ;

    }

    int m = (l+r) >> ;

    if(p <= m) update(p, x, ls);

    else update(p, x, rs);

    push_up(rt);

}

Tree query(int L, int R, int rt, int l, int r) {

    if(L <= l && r <= R) return tree[rt];

    int m = (l + r) >> ;

    if(R <= m) return query(L, R, ls);

    else if(L > m) return query(L, R, rs);

    Tree lft = query(L, R, ls);

    Tree rit = query(L, R, rs);

    int sum = lft.sum+rit.sum;

    int lv = max(lft.lv, lft.sum+rit.lv);

    int rv = max(rit.rv, rit.sum+lft.rv);

    int ans = max(lft.rv+rit.lv, max(lft.ans, rit.ans));

    return Tree{sum, lv, rv, ans};

}

int main() {

    int n, m, x, y, op;

    scanf("%d", &n);

    build(, , n);

    scanf("%d", &m);

    while(m --) {

        scanf("%d%d%d", &op, &x, &y);

        if(op) {

            Tree res = query(x, y, , , n);

            printf("%d\n", res.ans);

        }

        else {

            update(x, y, , , n);

        }

    }

    return ;

}

345 区间dp,经典石子归并问题

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = ;

const int INF = 0x3f3f3f3f;

int a[N], sum[N], dp[N][N];

int main() {

    int n;

    while(~scanf("%d", &n)) {

        for (int i = ; i <= n; i++) scanf("%d", &a[i]);

        for (int i = ; i <= n; i++) sum[i] = sum[i-] + a[i];

        for (int l = ; l <= n; l ++) {

            for (int i = ; i+l- <= n; i++) {

                int j = i+l-;

                dp[i][j] = INF;

                for (int k = i; k < j; k++) {

                    dp[i][j] = min(dp[i][j], dp[i][k] + dp[k+][j] + ((sum[k]-sum[i-])%) * ((sum[j]-sum[k])%));

                }

            }

        }

        printf("%d\n", dp[][n]);

    }

    return ;

}

4580 折半枚举

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = , M = 1e6 + ;

int a[N], b[M];

int main() {

    int n;

    scanf("%d", &n);

    for (int i = ; i <= n; i++) scanf("%d", &a[i]);

    int cnt = ;

    for (int i = ; i <= n; i++) {

        for (int j = ; j <= n; j++) {

            for (int k = ; k <= n; k++) {

                b[++cnt] = a[i] * a[j] + a[k];

            }

        }

    }

    sort(b+, b++cnt);

    LL ans = ;

    for (int i = ; i <= n; i++) {

        for (int j = ; j <= n; j++) {

            for (int k = ; k <= n; k++) {

                if(a[i] != ) {

                    int t1 = lower_bound(b+, b++cnt, a[i]*(a[j]+a[k])) - b;

                    int t2 = upper_bound(b+, b++cnt, a[i]*(a[j]+a[k])) - b;

                    ans += t2-t1;

                }

            }

        }

    }

    printf("%d\n", ans);

    return ;

}

302 数学

#include<iostream>

#include<cstdio>

#include<cstring>

#include<vector>

#include<algorithm>

#include<cmath>

#include<vector>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

int main() {

    int T, n;

    scanf("%d", &T);

    while(T--) {

        scanf("%d", &n);

        int nn = n;

        int t = sqrt(*n);

        t++;

        if(t*(t-)/ >= n) t--;

        n -= t*(t-)/;

        if(t%==)printf("TERM %d IS %d/%d\n", nn, n, t-n+);

        else printf("TERM %d IS %d/%d\n", nn, t-n+, n);

    }

    return ;

}

423 状压dp，一开始写了个n*n*(1<<n)，后来发现每次不用枚举每个状态，只需枚举到上一行为止的所有状态就可以了，开个二维vector滚动保存状态，暴力水过？

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = ;

LL dp[(<<) + ][N];

int a[N][N];

bool vis[(<<) + ];

vector<int>sta[];

int main() {

    int T, n;

    scanf("%d", &T);

    while(T--) {

        scanf("%d", &n);

        for (int i = ; i <= n; i++) {

            for (int j = ; j <= n; j++) scanf("%d", &a[i][j]);

        }

        mem(dp, );

        dp[][] = ;

        int cur = ;

        sta[].clear();

        sta[].clear();

        sta[cur].pb();

        for (int i = ; i <= n; i++) {

            cur ^= ;

            sta[cur].clear();

            mem(vis, false);

            for (int j = ; j <= n; j++) {

                if(a[i][j]) {

                    for (int k = ; k < sta[-cur].size(); k++) {

                        if(!(sta[-cur][k] & ( << (j-)))) {

                            dp[sta[-cur][k]|( << (j-))][i] += dp[sta[-cur][k]][i-];

                            if(!vis[sta[-cur][k]|( << (j-))])sta[cur].pb(sta[-cur][k]|( << (j-))), vis[sta[-cur][k]|( << (j-))] = true;

                        }

                    }

                }

            }

        }

        printf("%lld\n", dp[(<<n)-][n]);

    }

    return ;

}

3266 离线+树状数组，先按询问的k排序，然后把从大到小（我的代码是从小到大，求的是小于等与k的）加入这些数的位置，然后只需要维护前缀和就可以了

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 3e4 + , M = 2e5 + ;

int id[N], a[N], bit[N], ans[M], n;

struct node {

    int l, r, k, id;

    bool operator < (const node & t) const {

        return k < t.k;

    }

}b[M];

bool cmp(int x, int y) {

    return a[x] < a[y];

}

void add(int x, int a) {

    while(x <= n) bit[x] += a, x += x&-x;

}

int query(int x) {

    int ans = ;

    while(x) ans += bit[x], x -= x&-x;

    return ans;

}

int main() {

    int q;

    scanf("%d", &n);

    for (int i = ; i <= n; i++) scanf("%d", &a[i]), id[i] = i;

    scanf("%d", &q);

    for (int i = ; i <= q; i++) scanf("%d%d%d", &b[i].l, &b[i].r, &b[i].k), b[i].id = i;

    sort(b+, b++q);

    sort(id+, id++n, cmp);

    int t = ;

    for (int i = ; i <= q; i++) {

        while(t <= n && a[id[t]] <= b[i].k) add(id[t], ), t++;

        ans[b[i].id] = b[i].r - b[i].l +  - query(b[i].r) + query(b[i].l-);

    }

    for (int i = ; i <= q; i++) printf("%d\n", ans[i]);

    return ;

}

3946 线段树每个节点开个vector, 然后二分求区间第k大，单次询问复杂度（logn)^3，二分一个logn，线段树一个logn，每个节点二分一个logn

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 1e5 + ;

int a[N];

vector<int>vc[N<<];

vector<int>node;

void build(int rt, int l, int r) {

    if(l == r) {

        scanf("%d", &a[l]);

        vc[rt].pb(a[l]);

        return ;

    }

    int m = (l+r) >> ;

    build(ls);

    build(rs);

    for (int i = l; i <= r; i++) vc[rt].pb(a[i]);

    sort(vc[rt].begin(), vc[rt].end());

}

void query(int L, int R, int rt, int l, int r) {

    if(L <= l && r <= R) {

        node.pb(rt);

        return ;

    }

    int m = (l+r) >> ;

    if(L <= m) query(L, R, ls);

    if(R > m) query(L, R, rs);

}

int cal(int x) {

    int ans = ;

    for (int i = ; i < node.size(); i++) {

        ans += lower_bound(vc[node[i]].begin(), vc[node[i]].end(), x) - vc[node[i]].begin();

    }

    return ans;

}

int main() {

    int n, m, l, r, k;

    scanf("%d%d", &n, &m);

    build(, , n);

    sort(a+, a++n);

    while(m--) {

        scanf("%d%d%d", &l, &r, &k);

        node.clear();

        query(l, r, , , n);

        l = , r = n;

        int md = (l+r+) >> ;

        while(l < r) {

            int cnt = cal(a[md]);

            if(cnt < k) l = md;

            else r = md - ;

            md = (l+r+) >> ;

        }

        printf("%d\n", a[md]);

    }

    return ;

}

16487 差分数组

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 1e4 + ;

int a[N];

int main() {

    int T, n, m, q, v, l, r;

    scanf("%d", &T);

    while(T--) {

        scanf("%d%d", &n, &m);

        mem(a, );

        for (int i = ; i <= m; i++) scanf("%d%d%d", &l, &r, &v), l++, r++, a[l] += v, a[r+] -= v;

        for (int i = ; i <= n; i++) a[i] += a[i-];

        scanf("%d", &q);

        for (int i = ; i <= q; i++) scanf("%d", &l), printf("%d\n", a[l+]);

    }

    return ;

}

4300 暴力水题

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

int main() {

    int n;

    scanf("%d", &n);

    int ans = ;

    for (int i = ; i <= n; i++) {

        for (int j = ; j * j <= i; j++) {

            if(i%j == ) ans++;

        }

    }

    printf("%d\n", ans);

    return ;

}

14932 lca水题

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 1e3 + ;

int anc[N][], deep[N];

vector<int>g[N];

bool vis[N];

void dfs(int o, int u) {

    deep[u] = deep[o] + ;

    for (int i = ; i < g[u].size(); i++) {

        anc[g[u][i]][] = u;

        for (int j = ; j < ; j++) anc[g[u][i]][j] = anc[anc[g[u][i]][j-]][j-];

        dfs(u, g[u][i]);

    }

}

int lca(int u, int v) {

    if(deep[u] > deep[v]) swap(u, v);

    for (int i = ; i >= ; i--) if(deep[anc[v][i]] >= deep[u]) v = anc[v][i];

    if(u == v) return u;

    for (int i = ; i >= ; i--) if(anc[u][i] != anc[v][i]) u = anc[u][i], v= anc[v][i];

    return anc[u][];

}

int main() {

    int T, n, t, u, v, m;

    scanf("%d", &T);

    for (int cs = ; cs <= T; cs++) {

        mem(vis, false);

        mem(deep, );

        scanf("%d", &n);

        for (int i = ; i <= n; i++) g[i].clear();

        for (int i = ; i <= n; i++) {

            scanf("%d", &t);

            while(t--) scanf("%d", &u), vis[u] = true, g[i].pb(u);

        }

        int rt = ;

        for (int i = ; i <= n; i++) if(!vis[i]) rt = i;

        dfs(, rt);

        scanf("%d", &m);

        printf("Case %d:\n", cs);

        while(m--) {

            scanf("%d%d", &u, &v);

            printf("%d\n", lca(u, v));

        }

    }

    return ;

}

32 kmp 或者字符串hash

kmp

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 1e6 + ;

const int MOD = 1e9 + ;

int nxt[N];

char a[N], b[N];

vector<int>ans;

int main() {

    int n, m;

    while(~scanf("%d", &n)){

        scanf("%s", a);

        scanf("%s", b);

        m = strlen(b);

        nxt[] = -;

        for (int i = ; i < n; i++) {

            int j = nxt[i-];

            while(a[j+] != a[i] && j >= ) j = nxt[j];

            if(a[j+] == a[i]) nxt[i] = j+;

            else nxt[i] = -;

        }

        int i = , j = ;

        ans.clear();

        while(j < m) {

            if(b[j] == a[i]) {

                i++;

                j++;

                if(i == n) ans.pb(j - n), i = nxt[i-]+;

            }

            else {

                if(i == ) j++;

                else i = nxt[i-]+;

            }

        }

        if(ans.size() == ) puts("");

        else {

            for (int i = ; i < ans.size(); i++) printf("%d\n", ans[i]);

        }

    }

    return ;

}

字符串hash

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 1e6 + ;

const int MOD = 1e9 + ;

const int base = ;

char a[N], b[N];

int H[N], p[N];

int get_H(int l, int r) {

    return (H[r] - 1LL * H[l-] * p[r-l+] % MOD + MOD)%MOD;

}

vector<int>ans;

int main() {

    int n, m;

    p[] = ;

    for (int i = ; i < N; i++)p[i] = (1LL * p[i-] * base)%MOD;

    while(~scanf("%d", &n)){

        scanf("%s", a+);

        int f = ;

        for (int i = ; i <= n; i++) f = (1LL * f * base + a[i] - 'a')%MOD;

        scanf("%s", b+);

        m = strlen(b+);

        for (int i = ; i <= m; i++) H[i] = (1LL * H[i-] * base + (b[i] - 'a'))%MOD;

        ans.clear();

        for (int i = ; i+n- <= m; i++) {

            if(get_H(i, i+n-) == f) ans.pb(i);

        }

        if(ans.size() == ) puts("");

        else {

            for (int i = ; i < ans.size(); i++) printf("%d\n", ans[i]-);

        }

    }

    return ;

}

我的傻逼写法：离线+指针，复杂度：Maxa * log(a) + n

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 1e5 + ;

pii Q[N];

int ans[N];

int main() {

    int T;

    scanf("%d", &T);

    for (int i = ; i <= T; i++) scanf("%d", &Q[i].fi), Q[i].se = i;

    sort(Q+, Q++T);

    int l = , c2 = , c5 = ;

    for (int i = ; i <= T; i++) {

        while(l < Q[i].fi) {

            l++;

            int t = l;

            while(t% == ) c2++, t /= ;

            while(t% == ) c5++, t /= ;

        }

        ans[Q[i].se] = min(c2, c5);

    }

    for (int i = ; i <= T; i++) printf("%d\n", ans[i]);

    return ;

}

正解：数学

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

int main() {

    int T, n;

    scanf("%d", &T);

    for (int i = ; i <= T; i++) {

        scanf("%d", &n);

        int ans = ;

        for (LL i = ; i <= n; i *= ) ans += n/i;

        printf("%d\n", ans);

    }

    return ;

}

7742 水题

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

//#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 5e5 + ;

int a[N];

int main() {

    int n;

    scanf("%d", &n);

    for (int i = ; i <= n; i++) scanf("%d", &a[i]);

    sort(a+, a++n);

    int c = ;

    for (int i = ; i <= n; i++) {

        if(a[i] != a[i-]) {

            if(c == ) return  * printf("%d\n", a[i-]);

            c = ;

        }

        else c++;

    }

    if(c == ) printf("%d\n", a[n]);

    return ;

}

54 java大数

import java.math.*;

import java.util.*;

public class Main {

    public static void main(String[] args) {

        Scanner reader = new Scanner(System.in);

        BigInteger d = new BigInteger("2");

        while(reader.hasNext()){

            BigInteger a = reader.nextBigInteger();

            BigInteger b = reader.nextBigInteger();

            BigInteger c = a.subtract(b);

            c = c.divide(d);

            System.out.println(c.add(b));

            System.out.println(c);

        }

    }

}

3442 快速幂

#include<bits/stdc++.h>

using namespace std;

#define LL long long

LL q_pow(LL n, LL k) {

    LL ans = ;

    while(k) {

        if(k&) ans = (ans * n) % ;

        n = (n*n) % ;

        k >>= ;

    }

    return ans;

}

int main() {

    int T;

    LL a, b;

    scanf("%d", &T);

    while(T--) {

        scanf("%lld%lld", &a, &b);

        printf("%lld\n", q_pow(a, b));

    }

    return ;

}

11515 贪心，每次取这个位置之后能达到的最近的位置，先把每个l和r标记为a[l] = r，然后求个后缀最小值，预处理或者树状数组都可以

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 1e5 + , M = 1e6 + ;

const int INF = 0x3f3f3f3f;

pii a[N];

int b[M], bit[M];

int mx;

void add(int x, int a) {

    while(x) bit[x] = min(bit[x], a), x -= x&-x;

}

int query(int x) {

    int ans = INF;

    while(x <= mx) ans = min(ans, bit[x]), x += x&-x;

    return ans;

}

int main() {

    int T, n;

    scanf("%d", &T);

    while(T--) {

        scanf("%d", &n);

        mx = ;

        for (int i = ; i <= n; i++) scanf("%d%d", &a[i].fi, &a[i].se), a[i].fi++, a[i].se++, mx = max(mx, a[i].se);

        //sort(a+1, a+1+n);

        mem(b, INF);

        mem(bit, INF);

        for (int i = ; i <= n; i++) b[a[i].fi] = min(b[a[i].fi], a[i].se);

        for (int i = ; i < mx; i ++) {

            if(b[i] != INF) add(i, b[i]); //cout << i << " " << b[i] << endl;

        }

        int st = , ans = ;

        while(st <= mx) {

            st = query(st);

            if(st == INF) break;

            else ans++;

        }

        printf("%d\n", ans);

    }

    return ;

}

39 完全背包

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = , M = 1e4 + ;

const int INF = 0x3f3f3f3f;

pii a[N];

int dp[M];

int main() {

    int T, n, e, f, w;

    scanf("%d", &T);

    while(T--) {

        scanf("%d%d", &e, &f);

        scanf("%d", &n);

        for (int i = ; i <= n; i++)scanf("%d%d", &a[i].fi, &a[i].se);

        mem(dp, INF);

        dp[] = ;

        w = f - e;

        for (int i = ; i <= n; i++) {

            for (int j = a[i].se; j <= w; j++) {

                dp[j] = min(dp[j], dp[j-a[i].se]+a[i].fi);

            }

        }

        if(dp[w] == INF) printf("This is impossible.\n");

        else printf("The minimum amount of money in the piggy-bank is %d.\n", dp[w]);

    }

    return ;

}

3273 离散化+树状数组+二分

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 2e5 + ;

pair<int, char> Q[N];

int a[N], bit[N], cnt[N], q;

char s[];

void add(int x, int a) {

    while(x <= q) bit[x] += a, x += x&-x;

}

int query(int x) {

    int ans = ;

    while(x) ans += bit[x], x -= x&-x;

    return ans;

}

int MP[N];

int main() {

    int t;

    scanf("%d", &q);

    for (int i = ; i <= q; i++) {

        scanf("%s%d", s, &t);

        Q[i] = mp(t, s[]);

        a[i] = t;

    }

    sort(a+, a++q);

    for (int i = ; i <= q; i++) {

        t = lower_bound(a+, a++q, Q[i].fi) - a;

        if(Q[i].se != 'K') {

            MP[t] = Q[i].fi;

            Q[i].fi = t;

        }

    }

    for (int i = ; i <= q; i++) {

        if(Q[i].se == 'I') {

            if(!cnt[Q[i].fi])add(Q[i].fi, ), cnt[Q[i].fi]++;

        }

        else if(Q[i].se == 'D') {

            if(cnt[Q[i].fi]) cnt[Q[i].fi]--, add(Q[i].fi, -);

        }

        else if(Q[i].se == 'K') {

            if(Q[i].fi > query(q)) {

                printf("invalid\n");

                continue;

            }

            int l = , r = q, m = (l+r) >> ;

            while(l < r) {

                if(query(m) < Q[i].fi) l = m+;

                else r = m;

                m = (l+r) >> ;

            }

            printf("%d\n", MP[m]);

        }

        else if(Q[i].se == 'C') {

            printf("%d\n", query(Q[i].fi-));

        }

    }

    return ;

}

5449 stack

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 2e3 + ;

char s[N];

int main() {

    int cs = ;

    while(~scanf("%s", s+)) {

        if(s[] == '-') break;

        int n = strlen(s+);

        int l = , ans = ;

        for (int i = ; i <= n; i++) {

            if(s[i] == '{') l++;

            else {

                if(l) l--;

                else ans++, l++;

            }

        }

        ans += l/;

        printf("%d. %d\n", ++cs, ans);

    }

    return ;

}

12471 dp+记忆化搜索

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = 2e3 + ;

int dp[N][N][];

int dir[][] = {, , -, -, -, };

int dfs(int a, int b, int t) {

    if(a <=  || b <= ) return -;

    if(~dp[a][b][t]) return dp[a][b][t];

    for (int i = ; i < ; i++) {

        if(i != t)dp[a][b][t] = max(dp[a][b][t], dfs(a+dir[i][], b+dir[i][], i)+);

    }

    return dp[a][b][t];

}

int main() {

    int T, h, a;

    mem(dp, -);

    scanf("%d", &T);

    while(T--) {

        scanf("%d%d", &h, &a);

        printf("%d\n", max(max(dfs(h, a, ), dfs(h, a, )), dfs(h, a, )));

    }

    return ;

}

24 java大数

import java.math.*;

import java.util.*;

public class Main {

    public static void main(String[] args) {

        Scanner reader = new Scanner(System.in);

        int t;

        long n;

        t = reader.nextInt();

        for (int i = 1; i <= t; i++) {

            n = reader.nextLong();

            BigInteger ans = new BigInteger("1");

            for (long j = 1; j <= n; j++) {

                ans = ans.multiply(BigInteger.valueOf(j));

            }

            System.out.println(ans);

        }

    }

}

9921 bfs水题

#include<bits/stdc++.h>

using namespace std;

#define fi first

#define se second

#define pi acos(-1.0)

#define LL long long

#define mp make_pair

#define pb push_back

#define ls rt<<1, l, m

#define rs rt<<1|1, m+1, r

#define ULL unsigned LL

#define pll pair<LL, LL>

#define pii pair<int, int>

#define piii pair<int,pii>

#define mem(a, b) memset(a, b, sizeof(a))

#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);

//head

const int N = ;

char s[N][N];

bool vis[N][N];

int n, m;

int dir[][] = {, , , , -, , , -, , -, -, , , , -, -};

queue<piii>q;

int main() {

    int cs = ;

    while(~scanf("%d%d", &n, &m)) {

        if(!n && !m) break;

        for (int i = ; i <= n; i++) scanf("%s", s[i]+);

        mem(vis, false);

        for (int i = ; i <= n; i++) {

            for (int j = ; j <= m; j++) {

                if(s[i][j] == 'A') {

                    q.push({, {i, j}});

                    vis[i][j] = true;

                }

            }

        }

        int ans = ;

        while(!q.empty()) {

            piii p = q.front();

            q.pop();

            ans = p.fi;

            for (int i = ; i < ; i++) {

                int x = p.se.fi + dir[i][];

                int y = p.se.se + dir[i][];

                if( <= x && x <= n &&  <= y && y <= m && !vis[x][y] && s[x][y] == s[p.se.fi][p.se.se]+) {

                    vis[x][y] = true;

                    ans = p.fi + ;

                    q.push({p.fi+, {x, y}});

                }

            }

        }

        printf("Case %d: %d\n", ++cs, ans);

    }

    return ;

}

总结1：按点赞数降序第一页都是水题，不过复习了之前学过的算法（线段树合并、区间dp之类的），学会了各种离线操作，所以不打算刷简单题了。

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