hdu1015 dfs暴力搜

很水的题吧，不过以后注意环这种要考虑头尾情况

为了省力素数表范围打错了，太坑了

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <string>
#include <queue>
#include <stack>
#include <algorithm>

const int inf = (1<<31)-1;
const int MAXN = 2e1;
const int MMAXN = 4e1;
using namespace std;

int vist[MAXN];
int ans[MAXN];
int prime[MMAXN];

int n;

void makePrime(){
    prime[0] = prime[1] = 1;
    for(int i=2;i<=sqrt(MMAXN);i++){
        if(!prime[i]){
            for(int j=2*i;j<MMAXN;j+=i){
                prime[j] = 1;
            }
        }
    }
}

void dfs(int x){
    if(x==n){
        if(!prime[ans[1]+ans[n]]){
            for(int i=1;i<n;i++){
                printf("%d ",ans[i]);
            }
            cout<<ans[n]<<endl;
        }
        return;
    }
    for(int i=2;i<=n;i++){
        if(!vist[i]&&!prime[i+ans[x]]){
            ans[x+1] = i;
            vist[i] = 1;
            dfs(x+1);
            vist[i] = 0;
        }
    }
}

int main()
{
    int cas = 0;
    makePrime();
    /*for(int i=0;i<MMAXN;i++){
        cout<<prime[i]<<" ";
    }*/
    while(scanf("%d",&n)!=EOF){
        memset(vist,0,sizeof(vist));
        vist[1] = 1;
        ans[1] = 1;
        printf("Case %d:
",++cas);
            dfs(1);
        cout<<endl;
    }
   // cout << "Hello world!" << endl;
    return 0;
}