HDU 1016 prime ring Problem

Simple DFS, from 1 ~ N is composed of digits. Two Adjacent numbers are required to form a prime number.

The input is relatively small. You can screen out the prime number or directly judge it.

    CLR(prime,0);    prime[1]=1;    for(int i=2;i<101;i++)    for(int j=2;i*j<101;j++)    prime[i*j]=1;

Then, run the DFS command again.

#include<cstdio>#include<cstring>#include<string>#include<queue>#include<algorithm>#include<map>#include<stack>#include<iostream>#include<list>#include<set>#include<vector>#include<cmath>#define INF 0x7fffffff#define eps 1e-8#define LL long long#define PI 3.141592654#define CLR(a,b) memset(a,b,sizeof(a))#define FOR(i,a,n) for(int i= a;i< n ;i++)#define debug puts("==fuck==")#define acfun std::ios::sync_with_stdio(false)#define SIZE 1000+10using namespace std;int n;int a[21];bool vis[21];bool prime[101];void dfs(int m){    if(m>n)    {        FOR(i,0,n-1)        printf("%d ",a[i]);        printf("%d\n",a[n-1]);    }    else if(m==n)    {        if(!prime[a[m-1]+1])            dfs(m+1);    }    else    {        FOR(k,2,n+1)        {            if(!prime[a[m-1]+k]&&!vis[k])            {                vis[k]=1;                a[m]=k;                dfs(m+1);                vis[k]=0;            }        }    }}int main(){    CLR(prime,0);    prime[1]=1;    for(int i=2;i<101;i++)    for(int j=2;i*j<101;j++)    prime[i*j]=1;    int cot=1;    while(~scanf("%d",&n))    {        printf("Case %d:\n",cot++);        CLR(vis,0);        vis[1]=1;        a[0]=1;        dfs(1);        printf("\n");    }}

HDU 1016 prime ring Problem