hdu 1016

来源：互联网发布：最新网络语编辑：程序博客网时间：2024/06/06 05:54

经典深搜，注意那个顺时针与逆时针序，其实只用考虑顺时针就好，也就是说只要考虑与前一个数相加是否为素数即可。题不难，主要是对dfs递归理解要到位O(∩_∩)O~~

#include<iostream>#include<cstring>using namespace std;int n;int num[21],mark[21];int prime[12] = { 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37 };int isPrime(int b){for (int i=0; i<12; i++){if (b == prime[i]){return 1;}}return 0;}void dfs(int step){if (step-1==n && isPrime(num[step-1]+1)){for (int i=1; i<n; i++){printf("%d ",num[i]);}printf("%d\n",num[n]);return;}for (int i=2; i<=n; i++){if (mark[i] && isPrime(num[step-1]+i))  //标记为1是没用过,为0是用过 {num[step] = i;mark[i] = 0;dfs(step+1);mark[i] = 1;}}}int main(){int cont = 1;while (scanf("%d",&n) != EOF){memset(mark,0,sizeof(mark));memset(num,0,sizeof(num));printf("Case %d:\n",cont++);for (int i=1; i<=n; i++){mark[i] = 1;}num[1] = 1;if (n==1){printf("1\n\n");continue;}dfs(2);printf("\n");}}

0 0