HDU 1492 The number of divisors(约数) about Humble Numbers

http://acm.hdu.edu.cn/showproblem.php?pid=1492

计算约数的个数，由已知条件"A number whose only prime factors are 2,3,5 or 7 is called a humble number."简化运算。

View Code

#include <stdio.h>

__int64 find(__int64 n,int a)

{

    __int64 ans=0;

    while(1)

    {

        if(n==1)break;

        if(n%a==0)

        {

            ans++;

            n/=a;

        }

        else break;

    }

    return ans;

}

int main()

{

    __int64 n,ans;

    int cnt1,cnt2,cnt3,cnt4;

    while(scanf("%I64d",&n),n)

    {

        cnt1=cnt2=cnt3=cnt4=1;

        cnt1+=find(n,2);

        cnt2+=find(n,3);

        cnt3+=find(n,5);

        cnt4+=find(n,7);

        ans=cnt1*cnt2*cnt3*cnt4;

        printf("%I64d\n",ans);

    }

    return 0;

}