Prime Ring Problem

Time Limit: 4000/2000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 27754 Accepted Submission(s): 12338

Problem Description 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.

Input n (0 < n < 20).

Output 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.

Sample Input

6
8

Sample Output

Case 1:
1 4 3 2 5 6
1 6 5 2 3 4

Case 2:
1 2 3 8 5 6 7 4
1 2 5 8 3 4 7 6
1 4 7 6 5 8 3 2
1 6 7 4 3 8 5 2#include
   
    
#include
    
      int n; int prime[30]={1,1,0}; int way[30]; //存储最后结果序列 int visit[30]; //vis表示是否访问 void isprime() //不是素数标记为1 { int i,j; for(i=2;i<30;i++) { for(j=2*i;j<30;j+=i) { prime[j]=1; } } } void dfs(int temp) //环当前位置 { int i; if(temp==n && prime[way[0]+way[n-1]]==0)//若到达边界且首尾两个数字相加满足素数 { for(i=0;i

HDoj-1016-Prime Ring Problem-DFS

Prime Ring Problem