题意:
给一个数独的状态，判断它是否合法。
分析：
水，直接判断。
代码：
//poj 3435//sep9#include <iostream>using namespace std;const int maxN=10;const int MAX=maxN*maxN+10;int a[MAX][MAX];int col_check[MAX][MAX];int row_check[MAX][MAX];int grid_check[MAX][MAX];int n,c,r;bool check(){memset(row_check,0,sizeof(row_check));memset(col_check,0,sizeof(col_check));memset(grid_check,0,sizeof(grid_check));for(int i=0;i<r;++i)for(int j=0;j<c;++j)if(a[i][j]!=0){if(row_check[i][a[i][j]]!=0)return false;if(col_check[j][a[i][j]]!=0)return false;int g=i/n*n+j/n;if(grid_check[g][a[i][j]]!=0)return false;row_check[i][a[i][j]]=1;col_check[j][a[i][j]]=1;grid_check[g][a[i][j]]=1;}return true;}int main(){scanf("%d",&n);c=r=n*n;for(int i=0;i<r;++i)for(int j=0;j<c;++j)scanf("%d",&a[i][j]);if(check())puts("CORRECT");elseputs("INCORRECT");return 0;}
，记忆的屏障，曾经心动的声音已渐渐远去。
