hdu1016 Prime Ring Problem

//经典搜索题 
#include <iostream>
#include <cstring>
using namespace std;

int primelist[38] = {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};
//素数表， 
int n;
int A[21];   
//存放序列结果 
int vis[21];
//访问标记 

void DFS(int cur)
{
     if(cur == n && primelist[A[n-1]+A[0]])    //结束条件 
     {
            cout<<A[0];
            for(int i = 1; i < n; ++i)
            {
                    cout<<" "<<A[i];       
            }
            cout<<endl;
     }
     else
     {
            for(int i = 2; i <= n;++i)
            {
                    if(!vis[i] && primelist[i + A[cur-1]])   //如果i没有用过并且能与前面的数和成素数 
                    {
                              A[cur] = i;    //标记i已访问 
                              vis[i] = 1;    //将i加入结果序列 
                              DFS(cur+1);    //递归访问 
                              vis[i] = 0;    //回溯法标准框架去掉标记 
                    }
            }
     }
}

int main()
{
    int count = 0;
    A[0] = 1;
    while(cin>>n)
    {
          memset(vis,0,sizeof(vis));
          count++;
          cout<<"Case "<<count<<":"<<endl;
          DFS(1);
          cout<<endl;
    }
    return 0;
}

刘汝佳白书上的题目，回溯法标准框架
自Fenice  CSDN