hdu 2553 N皇后问题(dfs+回溯)

#include<stdio.h>
#include<iostream>
#include<string.h>
using namespace std;
int vis[3][23],p[15];
int n,sum;
void dfs(int row)
{
if(row==n+1)
{
sum++;
return;
}
for(int i=1;i<=n;i++)
{
if(vis[0][row-i+n]==0&&vis[1][i]==0&&vis[2][row+i]==0)
{
vis[0][row-i+n]=vis[1][i]=vis[2][row+i]=1;
dfs(row+1);//深搜
vis[0][row-i+n]=vis[1][i]=vis[2][row+i]=0;//回溯
}
}
}
int main()
{
for(n=1;n<=10;n++)//打个表不会超时
{
memset(vis,0,sizeof(vis));
sum=0;
dfs(1);
p
=sum;
}
//freopen("input.txt","r",stdin);
// freopen("output.txt","w",stdout);
while(~scanf("%d",&n)&&n)
{
printf("%d\n",p
);
}
return 0;
}