hdu 素數環1016
阿新 • • 發佈:2019-02-01
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.
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.
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<iostream> using namespace std; int N; int PrimeCycle[20]; int visited[20]; bool IsPrime(int num) { for (int i = 2; i*i <= num; i++) { if (num%i == 0) return false; } return true; } void dfs(int current,int size) { if (size == N+1) { if (IsPrime(current + 1)) { for (int i = 1; i < N; i++) { cout << PrimeCycle[i] << " "; } cout << PrimeCycle[N]; cout << endl; } return; } else { for (int i = 2; i <= N; i++) { if (visited[i]==0 && IsPrime(current + i)) { PrimeCycle[size] = i; visited[i] = 1; dfs(i,size+1); visited[i] = 0; } } } } int main() { int Case = 1; PrimeCycle[1] = 1; while (cin >> N) { cout << "Case " << Case++ << ":" << endl; dfs(1, 2); cout << endl; } return 0; }