poj2155 Matrix

思路：

二维树状数组。点修改区间查询转化为区间修改点查询。

http://blog.csdn.net/z309241990/article/details/9615259

http://blog.csdn.net/acm_BaiHuzi/article/details/46819049

实现：

#include <iostream>
#include <cstring>
using namespace std;
const int MAXN = 1005; 
int bit[MAXN][MAXN], x, n, t;

int lowbit(int x)
{
    return x & -x;
}

void add(int x, int y, int d)
{
    for (int i = x; i <= n; i += lowbit(i))
    {
        for (int j = y; j <= n; j += lowbit(j))
        {
            bit[i][j] += d;
        }
    }
}

int sum(int x, int y)
{
    int ans = 0;
    for (int i = x; i > 0; i -= lowbit(i))
    {
        for (int j = y; j > 0; j -= lowbit(j))
        {
            ans += bit[i][j];
        }
    }
    return ans;
}

int main()
{
    ios::sync_with_stdio(false);
    cin >> x;
    char c; int x1, y1, x2, y2;
    while (x--)
    {
        memset(bit, 0, sizeof bit);
        cin >> n >> t;
        for (int i = 0; i < t; i++)
        {
            cin >> c;
            if (c == 'Q') 
            {
                cin >> x1 >> y1;
                cout << (sum(x1, y1) & 1) << endl;
            }
            else
            {
                cin >> x1 >> y1 >> x2 >> y2;
                add(x1, y1, 1);
                add(x1, y2 + 1, -1);
                add(x2 + 1, y1, -1);
                add(x2 + 1, y2 + 1, 1);
            }    
        }
        cout << endl;
    }
    return 0;
}