二分+树状数组/线段树(区间更新) HDOJ 4339 Query

题目传送门

题意：给两串字符串，操作1：替换其中一个字符串的某个位置的字符 操作2：查询从p开始相等的最长连续长度

分析：树状数组可以维护一个区间内公共长度(连续)的情况，查询时用二分查找最远的端点即可。还可以用线段树去做，线段树能处理的问题很多，这题只要往右区间合并就行了。

收获：1.线段树的区间合并又做一题(虽然我写的还没AC) 2. 树状数组写起来方便又奇效！

代码1(树状数组)：

/************************************************
* Author        :Running_Time
* Created Time  :2015-8-26 9:46:09
* File Name     :I.cpp
 ************************************************/

#include <cstdio>
#include <algorithm>
#include <iostream>
#include <sstream>
#include <cstring>
#include <cmath>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <list>
#include <map>
#include <set>
#include <bitset>
#include <cstdlib>
#include <ctime>
using namespace std;

#define lson l, mid, rt << 1
#define rson mid + 1, r, rt << 1 | 1
typedef long long ll;
const int N = 1e6 + 10;
const int Q = 1e5 + 10;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + 7;
char s1[N], s2[N];
int L;
struct BIT   {
    int c[N];
    void init(void) {
        memset (c, 0, sizeof (c));
    }
    void updata(int i, int x)   {
        while (i <= L)   {
            c[i] += x;  i += (i & (-i));
        }
    }
    int query(int i)    {
        int ret = 0;
        while (i)   {
            ret += c[i];    i -= (i & (-i));
        }
        return ret;
    }
    int bsearch(int p, int l, int r)    {
        while (l <= r)  {
            int mid = (l + r) >> 1;
            if (query (mid) - query (p-1) == mid - p + 1)   l = mid + 1;
            else    r = mid - 1;
        }
        return l - p;
    }
}bit;

int main(void)    {
    int T, cas = 0; scanf ("%d", &T);
    while (T--) {
        scanf ("%s%s", s1 + 1, s2 + 1);
        int q;  scanf ("%d", &q);
        int len1 = strlen (s1 + 1), len2 = strlen (s2 + 1);
        L = min (len1, len2);

        bit.init ();
        for (int i=1; i<=L; ++i)    {
            if (s1[i] == s2[i]) bit.updata (i, 1);
        }
        printf ("Case %d:\n", ++cas);
        while (q--) {
            int op; scanf ("%d", &op);
            if (op == 1)    {
                int x, p;   char c; scanf ("%d%d %c", &x, &p, &c);
                ++p;
                if (p > L) continue;
                bool same = (s1[p] == s2[p]);
                if (x == 1) {
                    s1[p] = c;
                    if (same && s1[p] != s2[p])   bit.updata (p, -1);
                    else if (!same && s1[p] == s2[p])   bit.updata (p, 1);
                }
                else    {
                    s2[p] = c;
                    if (same && s1[p] != s2[p])   bit.updata (p, -1);
                    else if (!same && s1[p] == s2[p])   bit.updata (p, 1);
                }
            }
            else    {
                int p;  scanf ("%d", &p);
                ++p;
                if (p > L) {
                    puts ("0"); continue;
                }
                printf ("%d\n", bit.bsearch (p, p, L));
            }
        }
    }

    return 0;
}

代码2(线段树)：

/************************************************
* Author        :Running_Time
* Created Time  :2015-8-26 9:46:09
* File Name     :I.cpp
 ************************************************/

#include <cstdio>
#include <algorithm>
#include <iostream>
#include <sstream>
#include <cstring>
#include <cmath>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <list>
#include <map>
#include <set>
#include <bitset>
#include <cstdlib>
#include <ctime>
using namespace std;

#define lson l, mid, rt << 1
#define rson mid + 1, r, rt << 1 | 1
typedef long long ll;
const int N = 1e6 + 10;
const int Q = 1e5 + 10;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + 7;
char s1[N], s2[N];
struct ST   {
    int sum[N<<2];
    void push_up(int rt, int len)    {      //sum[rt<<1]表示从左子树线段左端点开始最长连续的公共的长度，如果全是公共的，
        if (sum[rt<<1] == len - (len >> 1)) sum[rt] = sum[rt<<1] + sum[rt<<1|1];        //合并右子树的线段长度
        else    sum[rt] = sum[rt<<1];
    }
    void build(int l, int r, int rt)    {
        if (l == r) {
            sum[rt] = s1[l] == s2[r] ? 1 : 0;
            return ;
        }
        int mid = (l + r) >> 1;
        build (lson);   build (rson);
        push_up (rt, r - l + 1);
    }
    void updata(int p, int c, int l, int r, int rt)    {
        if (l == r) {
            sum[rt] = c;  return ;
        }
        int mid = (l + r) >> 1;
        if (p <= mid)   updata (p, c, lson);
        else    updata (p, c, rson);
        push_up (rt, r - l + 1);
    }
    int query(int p, int l, int r, int rt)  {
        if (l == r) return sum[rt];
        int mid = (l + r) >> 1;
        if (p <= mid)   {
            int ret = query (p, lson);
            if (p + ret - 1 == mid) return ret + sum[rt<<1|1];
            else    return ret;
        }
        else    return query (p, rson);
    }
}st;

int main(void)    {
    int T, cas = 0; scanf ("%d", &T);
    while (T--) {
        scanf ("%s%s", s1 + 1, s2 + 1);
        int q;  scanf ("%d", &q);
        int len1 = strlen (s1 + 1), len2 = strlen (s2 + 1);
        int mn = min (len1, len2);
        st.build (1, mn, 1);

        printf ("Case %d:\n", ++cas);
        while (q--) {
            int op; scanf ("%d", &op);
            if (op == 1)    {
                int x, p;   char c; scanf ("%d%d %c", &x, &p, &c);
                ++p;
                if (p > mn) continue;                       //特殊情况特判
                if (x == 1) {
                    s1[p] = c;
                }
                else    {
                    s2[p] = c;
                }
                st.updata (p, (s1[p] == s2[p]), 1, mn, 1);
            }
            else    {
                int p;  scanf ("%d", &p);
                ++p;
                if (p > mn) {                               //特殊情况特判
                    puts ("0"); continue;
                }
                printf ("%d\n", st.query (p, 1, mn, 1));
            }
        }
    }

    return 0;
}

代码3(unAC)：

/************************************************
* Author        :Running_Time
* Created Time  :2015-8-26 9:46:09
* File Name     :I.cpp
 ************************************************/

#include <cstdio>
#include <algorithm>
#include <iostream>
#include <sstream>
#include <cstring>
#include <cmath>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <list>
#include <map>
#include <set>
#include <bitset>
#include <cstdlib>
#include <ctime>
using namespace std;

#define lson l, mid, rt << 1
#define rson mid + 1, r, rt << 1 | 1
typedef long long ll;
const int N = 1e6 + 10;
const int Q = 1e5 + 10;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + 7;
char s1[N], s2[N];
struct ST   {
    int sum[N<<2], lsum[N<<2], rsum[N<<2];
    void push_up(int rt, int len)    {
        lsum[rt] = lsum[rt<<1];
        rsum[rt] = rsum[rt<<1|1];
        sum[rt] = max (sum[rt<<1], sum[rt<<1|1]);
        if (lsum[rt] == len - (len >> 1))   lsum[rt] += lsum[rt<<1|1];
        if (rsum[rt] == len >> 1)   rsum[rt] += rsum[rt<<1];
        sum[rt] = max (rsum[rt<<1] + lsum[rt<<1|1], max (sum[rt<<1], sum[rt<<1|1]));
    }
    void build(int l, int r, int rt)    {
        if (l == r) {
            sum[rt] = lsum[rt] = rsum[rt] = s1[l] == s2[r] ? 1 : 0;
            return ;
        }
        int mid = (l + r) >> 1;
        build (lson);   build (rson);
        push_up (rt, r - l + 1);
    }
    void updata(int p, int c, int l, int r, int rt)    {
        if (l == r) {
            sum[rt] = lsum[rt] = rsum[rt] = c;  return ;
        }
        int mid = (l + r) >> 1;
        if (p <= mid)   updata (p, c, lson);
        else    updata (p, c, rson);
        push_up (rt, r - l + 1);
    }
    int query(int p, int l, int r, int rt)  {
        if (l == r) return sum[rt];
        int mid = (l + r) >> 1;
        if (p <= mid)   {
            if (p + rsum[rt<<1] - 1 >= mid)    return mid - p + 1 + query (p, rson);
            else    return query (p, lson);
        }
        else    return query (p, lson);
    }
}st;

int main(void)    {
    int T, cas = 0; scanf ("%d", &T);
    while (T--) {
        scanf ("%s%s", s1 + 1, s2 + 1);
        int q;  scanf ("%d", &q);
        int len1 = strlen (s1 + 1), len2 = strlen (s2 + 1);
        int mn = min (len1, len2);
        st.build (1, mn, 1);

        printf ("Case %d:\n", ++cas);
        while (q--) {
            int op; scanf ("%d", &op);
            if (op == 1)    {
                int x, p;   char c; scanf ("%d%d %c", &x, &p, &c);
                if (p + 1 > mn) continue;
                if (x == 1) {
                    s1[p+1] = c;
                }
                else    {
                    s2[p+1] = c;
                }
                st.updata (p+1, (s1[p+1] == s2[p+1]), 1, mn, 1);
            }
            else    {
                int p;  scanf ("%d", &p);
                if (p + 1 > mn) {
                    puts ("0"); continue;
                }
                printf ("%d\n", st.query (p + 1, 1, mn, 1));
            }
        }
    }

    return 0;
}