#include<iostream>#include<cstdio>#include<algorithm>#include<cstring>#define maxn 25#define inf 0x3f3f3f3fusing namespace std;int n;int a[maxn];bool vis[maxn];bool prime(int n){for(int i=2;i*i<=n;i++){if(n%i==0)return false;}return n!=1;}void dfs(int cur){if(cur>n){if(prime(a[cur-1]+1)){ //他是一个环，，最后要记得判断最后一个和第一个和是否为质数for(int i=1;i<=n;i++){if(i!=n)printf("%d ",a[i]);else printf("%d\n",a[i]);}}return ;}for(int i=2;i<=n;i++){if(prime(a[cur-1]+i)&&vis[i]==false){vis[i]=true;a[cur]=i;dfs(cur+1);vis[i]=false;}}}int main(){int i=1;//freopen("in.txt","r",stdin);while(scanf("%d",&n)!=EOF&&n){memset(vis,0,sizeof vis);printf("%s %d%s\n","Case",i++,":");vis[1]=true;a[1]=1;dfs(2);puts("");}}<div class="hiddable" id="vj_description" style="font-family: 'times new roman'; font-size: 17px; color: rgb(34, 34, 34);"><p class="pst" style="font-family: Arial, Helvetica, sans-serif; font-size: 18pt; font-weight: bold; color: blue; margin-bottom: 0px;">Description</p><div class="textBG" style="background-color: rgb(234, 235, 255); border-top-left-radius: 10px; border-top-right-radius: 10px; border-bottom-right-radius: 10px; border-bottom-left-radius: 10px; padding: 10px; border-style: dotted; border-width: 2px;"><div class="panel_content">A ring is compose of n circles as shown in diagram. Put natural number 1, 2, …, n into each circle separately, and the sum of numbers in two adjacent circles should be a prime. Note: the number of first circle should always be 1. <img src="" alt="" /></div><div class="panel_bottom"> </div></div></div><div class="hiddable" id="vj_input" style="font-family: 'times new roman'; font-size: 17px; color: rgb(34, 34, 34);"><p class="pst" style="font-family: Arial, Helvetica, sans-serif; font-size: 18pt; font-weight: bold; color: blue; margin-bottom: 0px;">Input</p><div class="textBG" style="background-color: rgb(234, 235, 255); border-top-left-radius: 10px; border-top-right-radius: 10px; border-bottom-right-radius: 10px; border-bottom-left-radius: 10px; padding: 10px; border-style: dotted; border-width: 2px;"><div class="panel_content">n (0 < n < 20). </div><div class="panel_bottom"> </div></div></div><div class="hiddable" id="vj_output" style="font-family: 'times new roman'; font-size: 17px; color: rgb(34, 34, 34);"><p class="pst" style="font-family: Arial, Helvetica, sans-serif; font-size: 18pt; font-weight: bold; color: blue; margin-bottom: 0px;">Output</p><div class="textBG" style="background-color: rgb(234, 235, 255); border-top-left-radius: 10px; border-top-right-radius: 10px; border-bottom-right-radius: 10px; border-bottom-left-radius: 10px; padding: 10px; border-style: dotted; border-width: 2px;"><div class="panel_content">The output format is shown as sample below. Each row represents a series of circle numbers in the ring beginning from 1 clockwisely and anticlockwisely. The order of numbers must satisfy the above requirements. Print solutions in lexicographical order. You are to write a program that completes above process. Print a blank line after each case. </div><div class="panel_bottom"> </div></div></div><div class="hiddable" id="vj_sampleInput" style="font-family: 'times new roman'; font-size: 17px; color: rgb(34, 34, 34);"><p class="pst" style="font-family: Arial, Helvetica, sans-serif; font-size: 18pt; font-weight: bold; color: blue; margin-bottom: 0px;">Sample Input</p><div class="textBG" style="background-color: rgb(234, 235, 255); border-top-left-radius: 10px; border-top-right-radius: 10px; border-bottom-right-radius: 10px; border-bottom-left-radius: 10px; padding: 10px; border-style: dotted; border-width: 2px;"><div class="panel_content"><pre style="white-space: pre-wrap; word-wrap: break-word;"><div style="font-family: 'Courier New', Courier, monospace;"> 68 </div>
Sample Output
Case 1:1 4 3 2 5 61 6 5 2 3 4Case 2:1 2 3 8 5 6 7 41 2 5 8 3 4 7 61 4 7 6 5 8 3 21 6 7 4 3 8 5 2
己欲立先立人，已欲达先达人。
