HDU2553-回溯-N皇后问题

#include <bits/stdc++.h>
using namespace std;
/*不知道为什么错，错误的写法

*/
const int maxn=30;
bool vis[maxn][maxn];
int m;
int sum;
queue<int>q;
void  dfs(int cengci){
if(cengci==m+1) {sum++;
/*cout<<cengci<<"!!!!!"<<endl;
for(int i=1;i<=m;i++){
for(int j=1;j<=m;j++)
if(vis[i][j])
cout<<"1 ";
else
cout<<"0 ";
cout<<endl;
}
cout<<"________________________"<<endl;
queue<int>s=q;
while(!s.empty()){
int u=s.front();
cout<<u<<" ";
s.pop();
}
cout<<endl;
cout<<"***********************"<<endl;
q.pop();*/
return ;}
for(int i=1;i<=m;i++){
if(!vis[cengci][i]){
for(int x=1;x+i<=m+1&&cengci+x<=m+1;x++){
vis[cengci+x][x+i]=true;//对角线向下右侧
}
for(int x=1;cengci-x>=1&&i-x>=1;x++)
vis[cengci-x][i-x]=true;//对角线向下左
for(int x=1;cengci-x>=1&&i+x<=m;x++)
vis[cengci-x][i+x]=true;//对角线向上右
for(int x=1;i-x>=1&&cengci+x<=m+1;x++)
vis[cengci+x][i-x]=true;//对角线向上左
for(int x=1;x<=m;x++)
{vis[x][i]=true;//竖直，
vis[cengci][x]=true;//横向
}
dfs(cengci+1);
q.push(i);
for(int x=1;x+i<=m+1&&cengci+x<=m+1;x++)
vis[cengci+x][x+i]=false;
for(int x=1;i-x>=1&&cengci+x<=m+1;x++)
vis[cengci+x][i-x]=false;
for(int x=1;x<=m;x++)
{vis[x][i]=false;
vis[cengci][x]=false;
}
for(int x=1;cengci-x>=1&&i-x>=1;x++)
vis[cengci-x][i-x]=false;
for(int x=1;cengci-x>=1&&i+x<=m;x++)
vis[cengci-x][i+x]=false;
}
}
}
int main()
{
while(~scanf("%d",&m)){
sum=0;
memset(vis,false,sizeof(vis));
dfs(1);
printf("%d\n",sum);
}
return 0;
}

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;
const int maxn=20;
int vis[3][maxn];
int m;
int sum;
void dfs(int cengci){
if(cengci==m+1)
{sum++;return;}
for(int i=1;i<=m;i++){
if(!vis[0][i]&&!vis[1][cengci-i+m]&&!vis[2][cengci+i])
{    vis[0][i]=true;
vis[1][cengci-i+m]=true;
vis[2][cengci+i]=true;
dfs(cengci+1);
vis[0][i]=false;
vis[1][cengci-i+m]=false;
vis[2][cengci+i]=false;
}
}
}
int main()
{   int dp[11];
for(int i=1;i<=10;i++){
m=i;
memset(vis,false,sizeof(vis));
sum=0;
dfs(1);
dp[i]=sum;
}
while(~scanf("%d",&m)){
if(!m) break;
printf("%d\n",dp[m]);

}

return 0;
}