素数环:NYOJ--488--dfs||hdu-1016-Prime Ring Problem

/*
    Name: NYOJ--488--素数环
    Author: shen_渊 
    Date: 15/04/17 15:30
    Description: DFS,素数打个表，37以内就够用了
*/

#include<cstring>
#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
void dfs(int);
int n;
//int prime[25] = {2,3,5,7,11,13,17,19,23,29,31,37};学到下面一招 
bool prime[45]={0,0,1,1,0,1,0,1,0,0,0,1,0,1,0,0,0,1,0,1,0,0,0,1,0,0,0,0,0,1,0,1,0,0,0,0,0,1,0,1,0,0};
int arr[22];
int vis[22];
int main() 
{
//    freopen("in.txt","r",stdin);
    int m = 0;
    while(cin>>n,n){
        memset(arr,0,sizeof(arr));
        memset(vis,0,sizeof(vis));
        arr[1] = 1;
        cout<<"Case "<<++m<<":\n";
        if(n == 1)cout<<"1\n";
        else if(n%2){
            cout<<"No Answer\n";
        }else{
            dfs(2);
        }
    }
    return 0;
}
void dfs(int ct){
    if(ct == n+1 && prime[arr[n]+arr[1]]){
            for(int i=1; i<=n; ++i)
                cout<<arr[i]<<" ";
            cout<<endl;
    }else{
        for(int i=2; i<=n; ++i){
            if(!vis[i] && prime[arr[ct-1]+i]){
                arr[ct] = i;
                vis[i] = 1;
                dfs(ct+1);
                vis[i] = 0;
            }
        }
    }
}

 因为用ios::sync_with_stdio(false);取消了C的stream和C++的stream的同步，所以输出出现了不符合预期的结果，以后还是少用cin,cout,scanf,printf，C和C++混合输出的方式

/*
    Name:hdu-1016-Prime Ring Problem 
    Copyright:
    Author:
    Date: 2018/5/19 16:59:52
    Description:水题 
*/
#include <cstring>
#include <iostream>
#include <cstdio>
using namespace std;
int n, arr[25], vis[25];
int prime[40]={0,1,1,1,0,1,0,1,0,0,0,1,0,1,0,0,0,1,0,1,0,0,0,1,0,0,0,0,0,1,0,1,0,0,0,0,0,1,0,0};//素数打表，因为n最大是20，所以只要打到40
bool jundge(int n) {
    for (int i=2; i*i<=n; i++) {
        if (n%i == 0) return 0;
    }
    return 1;
}
void dfs(int ct) {
    if (ct == n) {
        if (prime[arr[ct] + 1]) {
            cout<<arr[1];
            for (int i=2; i<=n; i++) {
                cout<<" "<<arr[i];
            }
            cout<<endl;
        }
    } else {
        for (int i=2; i<=n; i++) {
            if (vis[i] == 0 && prime[i+arr[ct]]) {
                arr[ct+1] = i;
                vis[i] = 1;
                dfs(ct+1);
                vis[i] = 0;
            }
        }
    }
}
int main()
{
//    ios::sync_with_stdio(false);
//    加上这一句，用printf输出WA，cout输出AC,测试后发现，用文件读取输入输出的时候，
//    printf并不能输出 Case 1：这一行的输出
    int k = 0;
    while (cin>>n) {
//        printf("Case %d:\n", ++k);
        cout<<"Case "<<++k<<":\n";
        if (n == 1) {
            cout<<"1\n\n";
            continue;
        }
        if (n & 1) {
            cout<<endl;
            continue;
        }
        memset(arr, 0, sizeof(arr));
        memset(vis, 0, sizeof(vis));
        arr[1] = 1;
        dfs(1);
        cout<<endl;
    }
    return 0;
}