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: 65536KTotal 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