HDU 1016

#include<stdio.h>
#include<string.h>
int isprime[40] = { 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0 };
int path[40];
int vis[40];
int n;
void dfs(int step)
{
if (step == n + 1 && isprime[path[1] + path[step - 1]])
{
for (int i = 1; i < n; i++)
printf("%d ", path[i]);
printf("%d\n", path[n]);
}
for (int i = 2; i <= n; i++)
{
if (!vis[i] && isprime[i + path[step - 1]])
{
path[step] = i;
vis[i] = 1;
dfs(step + 1);
vis[i] = 0;
}
}
}
int main()
{
int count = 1;
while (~scanf("%d", &n))
{
memset(vis, 0, sizeof(vis));
printf("Case %d:\n", count++);
path[1] = 1;
vis[1] = 1;
dfs(2);
printf("\n");
}
}