POJ2155 Matrix（树状数组）

给出一个矩阵，成块的修改一些值，原来是1变0，原来是0变1，询问某个点最后的值。

二维树状数组，再利用区间求和单点修改实现，最后只记录修改的次数，结果对2取余即为答案。

#include <iostream>
#include <stdio.h>
#include <string.h>
using namespace std;
const int N=1005;
int tree[N][N];
int n;

int lowbit(int i)
{
    return i&(-i);
}
void updata(int x,int y)
{
    for(int i=x;i<=n;i+=lowbit(i))
        for(int j=y;j<=n;j+=lowbit(j))
            tree[i][j]++;
}
int query(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+=tree[i][j];
    return ans;
}
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        memset(tree,0,sizeof(tree));
        int q;
        scanf("%d %d",&n,&q);
        while(q--)
        {
            char sym;
            scanf(" %c ",&sym);
            if(sym=='C')
            {
                int x1,y1,x2,y2;
                scanf("%d%d%d%d",&x1,&y1,&x2,&y2);
                updata(x1,y1);
                updata(x1,y2+1);
                updata(x2+1,y2+1);
                updata(x2+1,y1);
            }
            if(sym=='Q')
            {
                int x,y;
                scanf("%d%d",&x,&y);
                int ans=query(x,y);
                printf("%d\n",ans%2);
            }
        }
        printf("\n");
    }
    return 0;
}

Matrix

Time Limit: 3000MS		Memory Limit: 65536K
Total Submissions: 31005		Accepted: 11323

Description

Given an N*N matrix A, whose elements are either 0 or 1. A[i, j] means the number in the i-th row and j-th column. Initially we have A[i, j] = 0 (1 <= i, j <= N). 

We can change the matrix in the following way. Given a rectangle whose upper-left corner is (x1, y1) and lower-right corner is (x2, y2), we change all the elements in the rectangle by using "not" operation (if it is a '0' then change it into '1' otherwise change it into '0'). To maintain the information of the matrix, you are asked to write a program to receive and execute two kinds of instructions. 

1. C x1 y1 x2 y2 (1 <= x1 <= x2 <= n, 1 <= y1 <= y2 <= n) changes the matrix by using the rectangle whose upper-left corner is (x1, y1) and lower-right corner is (x2, y2). 
2. Q x y (1 <= x, y <= n) querys A[x, y]. 

Input

The first line of the input is an integer X (X <= 10) representing the number of test cases. The following X blocks each represents a test case. 

The first line of each block contains two numbers N and T (2 <= N <= 1000, 1 <= T <= 50000) representing the size of the matrix and the number of the instructions. The following T lines each represents an instruction having the format "Q x y" or "C x1 y1 x2 y2", which has been described above. 

Output

For each querying output one line, which has an integer representing A[x, y]. 

There is a blank line between every two continuous test cases. 

Sample Input

1
2 10
C 2 1 2 2
Q 2 2
C 2 1 2 1
Q 1 1
C 1 1 2 1
C 1 2 1 2
C 1 1 2 2
Q 1 1
C 1 1 2 1
Q 2 1

Sample Output

1
0
0
1