A ring is composed of n (even number) circles as shown in diagram. Put natural numbers
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.
n (0 < n <= 16)
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.
You are to write a program that completes above process.
6
8
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
Miguel A. Revilla
1999-01-11
解題策略
建立1到31的質數表，DFS走訪列舉16!，若有相鄰點和不是質數，就返回，減少遞迴的次數。