poj 2034 Anti-prime Sequences(dfs)

#include <stdio.h>
#include <iostream>
#include <map>
#include <stack>
#include <vector>
#include <math.h>
#include <string.h>
#include <queue>
#include <string>
#include <stdlib.h>
#include <algorithm>
#define LL long long
#define _LL __int64
#define eps 1e-8
#define PI acos(-1.0)
using namespace std;

const int maxn = 10010;

bool prime[maxn];
int vis[1010],ans[1010];
int n,m,d;
int ok;

void init()
{
memset(prime,true,sizeof(prime));
prime[0] = prime[1] = false;

for(int i = 2; i <= 10000; i++)
{
if(prime[i] == true)
{
for(int j = i*i; j <= 10000; j += i)
prime[j] = false;
}
}
}

void dfs(int dep)
{
if(ok == 1)
return;
if(dep == m-n+2)
{
ok = 1;
for(int i = 1; i < dep-1; i++)
printf("%d,",ans[i]);
printf("%d\n",ans[dep-1]);
return;
}

for(int i = n; i <= m; i++)
{
if(!vis[i])
{
bool flag = 0;

for(int k = 2; k <= d && dep-k>=0; k++)
{
int sum = 0;
for(int j = dep-k+1; j <= dep-1; j++)
sum += ans[j];
if(prime[sum + i] == true)
flag = 1;
}

if(flag == 1)
continue;

ans[dep] = i;
vis[i] = 1;

dfs(dep+1);

vis[i] = 0;
}
}
}

int main()
{
init();
while(~scanf("%d %d %d",&n,&m,&d))
{
if(n == 0 && m == 0 && d == 0) break;
memset(vis,0,sizeof(vis));
ok = 0;

dfs(1);

if(ok == 0)
printf("No anti-prime sequence exists.\n");
}
return 0;

}