題目鏈接：http://acm.hdu.edu.cn/showproblem.php?pid=1016

------------------------------------------------------------------------------------

題意：n個數，要求相鄰的兩個數之和為素數。

思路：DFS，深搜思想，把每種情況便利一遍。

代碼：

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<string
 
>
#include<vector>
#include<stack>
#include<bitset>
#include<cstdlib>
#include<cmath>
#include<set>
#include<list>
#include<deque>
#include<map>
#include<queue>
using namespace std;
typedef long long ll;
const double PI = acos(-1.0);
const
 
 double eps = 1e-6;
int n,cnt = 1;
int vis[21],A[21];
int isp[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};

void dfs(int cur)
{
    if(cur == n && isp[A[0] + A[n-1]]){
        printf("%d",A[0]);
        for(int i = 1;i < n;i++) printf(" %d",A[i]);
        printf("\n");
    }else
 
 for(int i = 2;i <= n;++i)
        if(!vis[i] && isp[i + A[cur-1]]){
            A[cur] = i;
            vis[i] = 1;
            dfs(cur + 1);
            vis[i] = 0;
        }
}

int main()
{
    A[0] = 1;
    while(~scanf("%d",&n))
    {
        for(int i=0;i<21;i++)    vis[i]=0;
        printf("Case %d:\n",cnt++);
        dfs(1);
        printf("\n");
    }

    return 0;
}

HDU 1016（DFS_B題）解題報告