【dfs】数独

 Luogu P1784 数独

dfsQAQ

枚举每个格子填什么， 符合要求的就填不符合的就不填qwq

#include<cstdio>
#include<cstring>
#include<cstdlib>
using namespace std;
const int sz = 10;
int plat[sz][sz];
bool h[sz][sz],l[sz][sz],small[sz][sz];
void print() {
    for(int i = 1; i <= 9; i++) {
        for(int j = 1; j <= 9; j++) {
            printf("%d ",plat[i][j]);
        }
        printf("
");
    }
    exit(0);
}
void dfs(int x, int y) {
    if(plat[x][y]) {
        if(x == 9 && y == 9) print();
        if(y == 9) dfs(x + 1, 1); 
        else dfs(x, y + 1);
    }
    if(!plat[x][y]) {
        for(int i = 1; i <= 9; i++) { 
            if(!h[x][i] && !l[y][i] && !small[(x-1)/3*3+(y-1)/3+1][i]) {
                plat[x][y] = i, h[x][i] = 1, l[y][i] = 1, small[(x - 1) / 3 * 3 + (y - 1) / 3 + 1][i] = 1;
                if(x == 9 && y == 9) print();
                if(y == 9) dfs(x + 1, 1); 
                else dfs(x, y + 1);
                plat[x][y] = 0, h[x][i] = 0, l[y][i] = 0, small[(x - 1) / 3 * 3 +(y - 1) / 3 + 1][i] = 0;
            }
        } 
    }
}
int main()
{
    for(int i = 1; i <= 9; i++) {
        for(int j = 1; j <= 9; j++) {
            scanf("%d", &plat[i][j]);
            if(plat[i][j]) {
                h[i][plat[i][j]] = 1;
                l[j][plat[i][j]] = 1;
                small[(i - 1) / 3 * 3 + (j - 1) / 3 + 1][plat[i][j]] = 1;
            }
        }
    } 
    dfs(1,1);
    return 0;
}

//以后玩数独有外挂啦qwq！！！！