hdu2642 Stars 二维树状数组

Problem:
给了一个矩阵，每次可以更新一个点的值，多次查询一个子矩阵的和。
Solution:
二维树状数组。

#include<cstdio>#include<iostream>#include<sstream>#include<cstdlib>#include<cmath>#include<cctype>#include<string>#include<cstring>#include<algorithm>#include<stack>#include<queue>#include<set>#include<map>#include<ctime>#include<vector>#include<fstream>#include<list>#include <iomanip>using namespace std;typedef long long ll;typedef unsigned long long ull;#define ms(s) memset(s,0,sizeof(s))const double PI = 3.141592653589;const int INF = 0x3fffffff;bool b[1010][1010];long long BI_tree[1010][1010];int nx, ny;inline int lowbit(int x) {    return x & -x;}void update(int x, int y, int v) {    for(int i = x; i <= nx; i += lowbit(i))        for(int j = y; j <= ny; j += lowbit(j))            BI_tree[i][j] += v;}long long query(int x, int y) {    long long ans = 0;    for(int i = x; i > 0; i -= lowbit(i))        for(int j = y; j > 0; j -= lowbit(j))            ans += BI_tree[i][j];    return ans;}int main() {//        freopen("/Users/really/Documents/code/input","r",stdin);    //    freopen("/Users/really/Documents/code/output","w",stdout);    ios::sync_with_stdio(false);    int m;    cin >> m;    nx = ny = 1001;    while(m--) {        char c;        int x, y, x1, y1;        cin >> c;        if(c == 'B') {            cin >> x >> y;            x++;  y++;            if(b[x][y] == false) {                update(x, y, 1);                b[x][y] = true;            }        }        else if(c == 'D') {            cin >> x >> y;            x++;  y++;            if(b[x][y] == true) {                update(x, y, -1);                b[x][y] = false;            }        }        else if(c == 'Q') {            cin >> x >> x1 >> y >> y1;            x++;  y++;  x1++;  y1++;            if(x1 < x)                swap(x, x1);            if(y1 < y)                swap(y, y1);            cout << query(x1, y1) - query(x-1, y1) - query(x1, y-1) + query(x-1, y-1) << endl;        }    }    return 0;}