HDU 1016 Prime Ring Problem 搜索题

#include<stdio.h>
#include<string.h>
#include <iostream>
using namespace std;
int N;
int prime[12]={2,3,5,7,11,13,17,19,23,29,31,37};
int ring[25];
int visited[25];
int search(int low ,int high,int x)
{
if(low>high)return 0;
int mid=(low+high)>>1;
if(x==prime[mid])return mid;
else if(x>prime[mid])
{
return search(mid+1,high,x);
}
return search(low,mid-1,x);
}
void DFS(int index,int primNum)
{
int i;
if(primNum==N&&search(1,11,index+1))
{
for( i=1;i<N;i++)
{
printf("%d ",ring[i]);
}
printf("%d\n",ring[N]);
return ;
}
for(i=1;i<=N;i++)
{
if(!visited[i]&&((index&1)!=(i&1))&& search(1,11,index+i))
{
visited[i]=1;
ring[primNum+1]=i;
DFS(i,primNum+1);
visited[i]=0;
ring[primNum+1]=0;
}
}

}
int main()
{
int cases=0;
while(scanf("%d",&N)!=EOF)
{
cases++;
memset(ring,0,sizeof(ring));
memset(visited,0,sizeof(visited));
printf("Case %d:\n",cases);
visited[1]=1;
ring[1]=1;
DFS(1,1);
printf("\n");
}
return 0;
}