深搜_八皇后(HDU_2553)

#include <stdio.h>
#include <string.h>

#define M 12

int map[M][M],n,sum;
int ini[M];

int jud(int row,int col)
{
    for(int i=1;i<row;i++)
    for(int j=1;j<=n;j++)
        if(map[i][j] && (row==i || col==j || i+j==row+col || i-j==row-col))    return 0;
    return 1;
}

void dfs(int row)
{
    if(row>n)
    {
        sum++;
        return ;
    }
    for(int i=1;i<=n;i++)
    {
        map[row][i]=1;
        if(jud(row,i))    dfs(row+1);
        map[row][i]=0;
    }
}

int main(int argc, char *argv[])
{
    #ifdef __LOCAL
    freopen("in.txt","r",stdin);
    #endif
    memset(ini,0,sizeof(ini));
    while(scanf("%d",&n) && n)
    {
        if(ini[n])
        {
            printf("%d\n",ini[n]);    continue;
        }
        sum=0;
        memset(map,0,sizeof(map));
        dfs(1);
        ini[n]=sum;
        printf("%d\n",sum);
    }
    return 0;
}