HDU OJ 1016 Prime Ring Problem

#include <iostream>
#include <stdio.h>
using namespace std;
int n,map[30],vis[30];
void dfs(int s[30], int x, int vis[30])
{
    int i, t, j,flag;
    if(x==n-1)
    {
        flag=0;
        t=s[x]+1;
        for(j=2;j<t;j++)
        {
            if(t%j==0)
            {
                flag=1;
                break;
            }
        }
        if(flag)
            return ;
        for(i=0;i<n;i++)
        {
            if(i!=n-1)
                printf("%d ",s[i]);
            else
                printf("%d\n",s[i]);
        }
        return ;
    }
    for(i=1;i<=n;i++)
    {
        if(!vis[i])
        {
            t=i+s[x];
            flag=0;
            for(j=2;j<t;j++)
            {
                if(t%j==0)
                {
                    flag=1;
                    break;
                }
            }
            if(flag==0)
            {
                vis[i]=1;
                s[x+1]=i;
                dfs(s,x+1,vis);
                vis[i]=0;
            }
        }
    }
}
int main()
{
    int num=0;
    while(scanf("%d",&n)!=EOF)
    {
        num++;
        memset(map,0,sizeof(map));
        memset(vis,0,sizeof(vis));
        vis[1]=1;
        map[0]=1;
        printf("Case %d:\n",num);
        dfs(map,0,vis);
        printf("\n");
    }
    return 0;
}
时间: 12-25

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