题目1459：Prime ring problem(素数环问题——递归算法)

题目链接：http://ac.jobdu.com/problem.php?pid=1459

详解链接：https://github.com/zpfbuaa/JobduInCPlusPlus

参考代码：

//
//  1459 Prime ring problem.cpp
//  Jobdu
//
//  Created by PengFei_Zheng on 23/04/2017.
//  Copyright © 2017 PengFei_Zheng. All rights reserved.
//

#include <stdio.h>
#include <iostream>
#include <algorithm>
#include <string.h>
#include <cmath>
#define PRIME 13
#define MAX_SIZE 21
using namespace std;

int n;
int ans[MAX_SIZE];
bool used[MAX_SIZE];

int prime[]={,,,,,,,,,,,,};
bool judge(int x){
    for(int i =  ; i < PRIME ; i++){
        if(prime[i]==x)
            return true;
    }
    return false;
}

void check(){
    if(!judge(ans[n]+ans[])) return;
    for(int i =  ; i <= n ; i++){
        if(i!=) printf(" ");
        printf("%d",ans[i]);
    }
    printf("\n");
}

void DFS(int num){
    if(num>){
        if(!judge(ans[num] + ans[num - ])) return;
    }
    if(num==n){
        check();
        return;
    }
    for(int i =  ; i <= n ; i++){
        if(!used[i]){
            used[i] = true;
            ans[num+] = i;
            DFS(num+);
            used[i] = false;
        }
    }
}

int main(){
    int kase = ;
    while(scanf("%d",&n)!=EOF){
        kase++;
        memset(used,false,sizeof(used));
        ans[] = ;
        used[]=true;
        printf("Case %d:\n",kase);
        DFS();
        printf("\n");
    }
    return ;
}
/**************************************************************
    Problem: 1459
    User: zpfbuaa
    Language: C++
    Result: Accepted
    Time:590 ms
    Memory:1520 kb
****************************************************************/