C++解答

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath> 
using namespace std;
int b[20]={0},a[20],sum=0;
int i,m,n,j,k;
int pd (int m)
{
 int i;
 for (i=2;i<=floor(sqrt(m));++i)
  if (m%i==0) return 0;
 return 1;
}
int pl (int s)
{
 int i,j;
 for (i=2;i<=n;++i)
  if ((b[i]==0)&&(pd(i+a[s-1])==1))
  {
  	a[s]=i;
  	b[i]=1;
  	if (s==n)
	 {
	  if (pd(a[20]+a[1])==1) 
	  {
	  sum+=1;if (sum>1) cout<<endl;
  	  for (j=1;j<=n;++j)
  	   if (j==1) cout<<a[j];
  	    else cout<<" "<<a[j]; 
  	  }
	 }
  	else pl(s+1);
  	b[i]=0;
  }
}
int main ()
{
 cin>>n;
 a[1]=1;
 pl(2);
 return 0;
}

Java解答

import java.util.Scanner;



public class Main {
	static int n;
	static int[] a = new int[50];
	static boolean[] vis = new boolean[50];
	static boolean[] isp = new boolean[50];

	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		while (in.hasNextInt()) {
			n = in.nextInt();
			a[0] = 1;
			for (int i = 2; i <= n * 2; i++)
				isp[i] = isPrime(i);
			dfs(1);
		}
	}

	public static void dfs(int cur) {
		if (cur == n && isp[a[n - 1] + a[0]]) {
			for (int i = 0; i < n; i++) {
				if (i == n - 1)
					System.out.println(a[i]);
				else
					System.out.print(a[i] + " ");
			}
		} else {
			for (int i = 2; i <= n; i++) {
				if (!vis[i] && isp[i + a[cur - 1]]) {
					a[cur] = i;
					vis[i] = true;
					dfs(cur + 1);
					vis[i] = false;
				}
			}
		}
	}
	public static boolean isPrime(int n) {
		if (n < 2)
			return false;
		for (int j = 2; j * j <= n; j++)
			if (n % j == 0)
				return false;
		return true;
	}
}