【HDOJ】4251 The Famous ICPC Team Again

划分树模板题目，主席树也可解。
划分树。

 /* 4251 */
 #include <iostream>
 #include <sstream>
 #include <string>
 #include <map>
 #include <queue>
 #include <set>
 #include <stack>
 #include <vector>
 #include <deque>
 #include <algorithm>
 #include <cstdio>
 #include <cmath>
 #include <ctime>
 #include <cstring>
 #include <climits>
 #include <cctype>
 #include <cassert>
 #include <functional>
 #include <iterator>
 #include <iomanip>
 using namespace std;
 //#pragma comment(linker,"/STACK:102400000,1024000")

 #define sti                set<int>
 #define stpii            set<pair<int, int> >
 #define mpii            map<int,int>
 #define vi                vector<int>
 #define pii                pair<int,int>
 #define vpii            vector<pair<int,int> >
 #define rep(i, a, n)     for (int i=a;i<n;++i)
 #define per(i, a, n)     for (int i=n-1;i>=a;--i)
 #define clr                clear
 #define pb                 push_back
 #define mp                 make_pair
 #define fir                first
 #define sec                second
 #define all(x)             (x).begin(),(x).end()
 #define SZ(x)             ((int)(x).size())
 #define lson            l, mid, rt<<1
 #define rson            mid+1, r, rt<<1|1

 const int maxn = 1e5+;
 int order[maxn];
 int toLeft[][maxn];
 int val[][maxn];
 int n;

 void Build(int l, int r, int dep) {
     if (l == r) {
         toLeft[dep][l] = toLeft[dep][l-] + ;
         return ;
     }

     int mid = (l + r) >> ;
     int same = mid - l + ;

     rep(i, l, r+) {
         if (val[dep][i] < order[mid])
             --same;
     }

     int lpos = l, rpos = mid + ;

     rep(i, l, r+) {
         if (val[dep][i] < order[mid]) {
             val[dep+][lpos++] = val[dep][i];
         } else if (val[dep][i]==order[mid] && same>) {
             val[dep+][lpos++] = val[dep][i];
             --same;
         } else {
             val[dep+][rpos++] = val[dep][i];
         }
         toLeft[dep][i] = toLeft[dep][l-] + lpos - l;
     }

     Build(l, mid, dep+);
     Build(mid+, r, dep+);
 }

 int Query(int l, int r, int k, int L, int R, int dep) {
     if (l == r) {
         return val[dep][l];
     }

     int mid = (L + R) >> ;
     int tmp = toLeft[dep][r] - toLeft[dep][l-];

     if (tmp >= k) {
         int ll = L + toLeft[dep][l-] - toLeft[dep][L-];
         int rr = ll + tmp - ;

         return Query(ll, rr, k, L, mid, dep+);
     } else {
         k -= tmp;
         int ll = mid+ + l-L - (toLeft[dep][l-] - toLeft[dep][L-]);
         int rr = ll + (r-l+-tmp) - ;

         return Query(ll, rr, k, mid+, R, dep+);
     }
 }

 void solve() {
     sort(order+, order++n);
     Build(, n, );

     int q;
     int l, r, kth;
     int ans;

     scanf("%d", &q);
     while (q--) {
         scanf("%d %d", &l, &r);
         kth = ((l+r)>>) - l + ;
         ans = Query(l, r, kth, , n, );
         printf("%d\n", ans);
     }
 }

 int main() {
     ios::sync_with_stdio(false);
     #ifndef ONLINE_JUDGE
         freopen("data.in", "r", stdin);
         freopen("data.out", "w", stdout);
     #endif

     int t = ;

     while (scanf("%d", &n)!=EOF) {
         rep(i, , n+) {
             scanf("%d", &val[][i]);
             order[i] = val[][i];
         }
         printf("Case %d:\n", ++t);
         solve();
     }

     #ifndef ONLINE_JUDGE
         printf("time = %d.\n", (int)clock());
     #endif

     return ;
 }

主席树。

 /* 4251 */
 #include <iostream>
 #include <sstream>
 #include <string>
 #include <map>
 #include <queue>
 #include <set>
 #include <stack>
 #include <vector>
 #include <deque>
 #include <algorithm>
 #include <cstdio>
 #include <cmath>
 #include <ctime>
 #include <cstring>
 #include <climits>
 #include <cctype>
 #include <cassert>
 #include <functional>
 #include <iterator>
 #include <iomanip>
 using namespace std;
 //#pragma comment(linker,"/STACK:102400000,1024000")

 #define sti                set<int>
 #define stpii            set<pair<int, int> >
 #define mpii            map<int,int>
 #define vi                vector<int>
 #define pii                pair<int,int>
 #define vpii            vector<pair<int,int> >
 #define rep(i, a, n)     for (int i=a;i<n;++i)
 #define per(i, a, n)     for (int i=n-1;i>=a;--i)
 #define clr                clear
 #define pb                 push_back
 #define mp                 make_pair
 #define fir                first
 #define sec                second
 #define all(x)             (x).begin(),(x).end()
 #define SZ(x)             ((int)(x).size())
 // #define lson            l, mid, rt<<1
 // #define rson            mid+1, r, rt<<1|1

 const int maxn = 1e5+;
 const int maxm = maxn * ;
 int a[maxn], b[maxn];
 int T[maxn];
 int lson[maxm], rson[maxm], c[maxm];
 int n, m, tot;

 void init() {
     m = tot = ;
 }

 int Build(int l, int r) {
     int rt = tot++;

     c[rt] = ;
     if (l == r)
         return rt;

     int mid = (l + r) >> ;

     lson[rt] = Build(l, mid);
     rson[rt] = Build(mid+, r);
     return rt;
 }

 int Insert(int rt, int p, int delta) {
     int nrt = tot++, ret = nrt;
     int l = , r = m - , mid;

     c[nrt] = c[rt] + delta;
     while (l < r) {
         mid = (l + r) >> ;
         if (p <= mid) {
             lson[nrt] = tot++;
             rson[nrt] = rson[rt];
             nrt = lson[nrt];
             rt = lson[rt];
             r = mid;
         } else {
             lson[nrt] = lson[rt];
             rson[nrt] = tot++;
             nrt = rson[nrt];
             rt = rson[rt];
             l = mid + ;
         }
         c[nrt] = c[rt] + delta;
     }

     return ret;
 }

 int Query(int lrt, int rrt, int k, int l, int r) {
     if (l == r)
         return l;

     int mid = (l + r) >> ;
     int tmp = c[lson[rrt]] - c[lson[lrt]];

     if (tmp >= k) {
         return Query(lson[lrt], lson[rrt], k, l, mid);
     } else {
         k -= tmp;
         return Query(rson[lrt], rson[rrt], k, mid+, r);
     }
 }

 void solve() {
     init();
     sort(b, b+n);
     m = unique(b, b+n) - b;
     T[] = Build(, m-);
     rep(i, , n) {
         int id = lower_bound(b, b+m, a[i]) - b;
         T[i+] = Insert(T[i], id, );
     }

     int q;
     int l, r, kth;
     int ans;

     scanf("%d", &q);
     while (q--) {
         scanf("%d %d", &l, &r);
         kth = ((l+r)>>)-l+;
         int id = Query(T[l-], T[r], kth, , m-);
         ans = b[id];
         printf("%d\n", ans);
     }
 }

 int main() {
     ios::sync_with_stdio(false);
     #ifndef ONLINE_JUDGE
         freopen("data.in", "r", stdin);
         freopen("data.out", "w", stdout);
     #endif

     int t = ;

     while (scanf("%d", &n)!=EOF) {
         rep(i, , n) {
             scanf("%d", &a[i]);
             b[i] = a[i];
         }
         printf("Case %d:\n", ++t);
         solve();
     }

     #ifndef ONLINE_JUDGE
         printf("time = %d.\n", (int)clock());
     #endif

     return ;
 }