NEU OJ 1649 GMZ’s Pretty Number

#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<queue>
#include<cstring>
using namespace std;
 
const long N = 10000000;
long long prime[N] = {0},num_prime = 0;
int isNotPrime[N] = {1, 1};
int R[10000000+10];
int ans[10000000+10];
int main()
{
    memset(R,0,sizeof(R));
    memset(ans,0,sizeof(ans));
    for(long i = 2 ; i < N ; i ++)
    {
        if(! isNotPrime[i])
            prime[num_prime ++]=i;
        //关键处1
        for(long j = 0 ; j < num_prime && i * prime[j] <  N ; j ++)
        {
            isNotPrime[i * prime[j]] = 1;
            if( !(i % prime[j] ) )  //关键处2
                break;
        }
    }
 
    for(int i=0;i<num_prime;i++)
    {
        for(int j=i+1;j<num_prime;j++)
        {
            if(prime[i]*prime[j]>10000000) break;
            R[prime[i]*prime[j]]=1;
        }
    }
    ans[0]=0;
    for(int i=1;i<=10000000;i++)
    {
        if(R[i]==1) ans[i]=ans[i-1]+1;
        else ans[i]=ans[i-1];
    }
    int LL,RR;
    while(~scanf("%d%d",&LL,&RR))
    {
        printf("%d\n",ans[RR]-ans[LL-1]);
    }
    return 0;
}