poj 3292 Semi-prime H-numbers

#include <iostream>            //线性筛+树状数组
#include<stdio.h>
using namespace std;
#define Max 1000010
int n,table[Max],vis[Max],prime[80000];
int lowbit(int x)
{
    return x&(-x);
}
void modify(int x)
{
    if(vis[x]==0)
    {
        vis[x]=1;
        while(x<Max)
        {
            table[x]++;
            x+=lowbit(x);
        }
    }
}
int getsum(int x)
{
    int s=0;
    while(x>0)
    {
        s+=table[x];
        x-=lowbit(x);
    }
    return s;
}
int main()
{
    int curr=9,rear=1;
    prime[1]=5;
    while(curr<Max/5)    //上界是Max/5
    {
        int tag=1;    
        for(int j=1;prime[j]*prime[j]<=curr;++j)        
        {    
            if(curr%prime[j]==0)
            {
                tag=0;break;
            }
        }
        if(tag==1)
            prime[++rear]=curr;
        curr+=4;
    }
    for(int i=1;prime[i]*prime[i]<Max;++i)        
        for(int j=i;j<=rear&&prime[i]*prime[j]<Max;++j)    //要添加j<=rear,因为当j的下标超过rear后，prime[j]=0,那么将无限循环下去
        {        
            modify(prime[i]*prime[j]);
        }

    while(scanf("%d",&n),n)
    {
        printf("%d %d\n",n,getsum(n));
    }
    return 0;
}