POJ 3292 Semi-prime H-numbers

H-number是指形如4n+1(n>=0)的整数，后又定义了好几种数。

水题。

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
#define N 1000002
bool NotaHprime[N],IsaHsemiprime[N];
int ans[N];
int main()
{
    int i,j;
    memset(NotaHprime,false,sizeof(NotaHprime));
    memset(IsaHsemiprime,false,sizeof(IsaHsemiprime));
    for (i=5; i<1002; i+=4)
    {
        for (j=i; i*j<N; j+=4)
        {
            NotaHprime[i*j]=true;
        }
    }
    for (i=5; i<1002; i+=4)
    {
        for (j=i; i*j<N; j+=4)
        {
            if (!NotaHprime[i] && !NotaHprime[j])
                IsaHsemiprime[i*j]=true;
        }
    }
    ans[1]=0;
    for (i=2; i<N; i++)
    {
        if (IsaHsemiprime[i])
            ans[i]=ans[i-1]+1;
        else
            ans[i]=ans[i-1];
    }
    while (1)
    {
        scanf("%d",&i);
        if (i == 0)
            break;
        printf("%d %d\n",i,ans[i]);
    }
}