poj 2676 Sudoku

经典的搜索题，我用的是简单的暴搜，其实这题用排除法做会更快。

#include <stdio.h>
#include <string.h>
#define index(a,b) 3*(a/3)+(b/3)
bool r[10][10],c[10][10],sodu[10][10];
int map[10][10];
bool find;
void dfs(int n)
{
    int i,j,k,x,y;
    if(find) return ;
    if(n >= 81)
    {
        find = 1;
        for(i = 0; i < 9; i++)
        {
            for(j = 0; j < 9; j++)
                printf("%d",map[i][j]);
            printf("\n");
        }
    }
    x = n/9;
    y = n%9;
    if(map[x][y]) dfs(n+1);
    else
    {
        for(k = 1; k <= 9; k++)
            if(!r[x][k] && !c[y][k] && !sodu[index(x,y)][k])
            {
                r[x][k] = c[y][k] = 1;
                sodu[index(x,y)][k] = 1;
                map[x][y] = k;
                dfs(n+1);
                r[x][k] = c[y][k] = 0;
                sodu[index(x,y)][k] = 0;
                map[x][y] = 0;
            }
    }
}
int main()
{
    int n,i,j,t;
    scanf("%d",&n);
    while(n--)
    {
        memset(map,0,sizeof map);
        memset(r,0,100);
        memset(c,0,100);
        memset(sodu,0,100);
        find = 0;
        for(i = 0; i < 9; i++)
            for(j = 0; j < 9; j++)
            {
                scanf("%1d",&map[i][j]);
                t = map[i][j];
                if (t)
                {
                    r[i][t] = 1;
                    c[j][t] = 1;
                    sodu[index(i,j)][t] = 1;
                }
            }
            dfs(0);
    }
    return 0;
}