HDU1016-素数环 暴力深搜


#include <iostream>
#include <cstdio>
#include <cstring>
#include <vector>
using namespace std;

int prime[42]={0,0,1,1,0,1,0,1,0,0,0,1,0,1,0,0,0,1,0,1,0,0,0,1,0,0,0,0,0,1,0,1,0,0,0,0,0,1,0,0,0,1};
int vis[20],ans[20];
int  n;
void dfs(int cnt)
{
    int i;
    if(cnt==n)//这里只有n个
    {
        if(prime[ans[n]+1])//处理最后一个
        {
            for(i=1;i<n;i++)
            printf("%d ",ans[i]);
            printf("%d\n",ans[i]);
        }
        return ;
    }
    for(i=1;i<=n;i++)
    {
        ans[cnt+1]=i;
        if(!vis[i]&&prime[ans[cnt]+ans[cnt+1]])
        {
            vis[i]=1;
            dfs(cnt+1);//递归深搜下一个
            vis[i]=0;
        }
    }
}
int main()
{

    int i,cnt;
    int t=1;
    while(cin>>n)
    {
        printf("Case %d:\n",t++);
        memset(vis,0,sizeof(vis));
         ans[1]=1;
         vis[1]=1;
         cnt=1;
         dfs(1);
        printf("\n");
    }
    return 0;
}