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

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

Problem Description

A number whose only prime factors are 2,3,5 or 7 is called a humble number. The sequence 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 24, 25, 27, ... shows the first 20 humble numbers.

Now given a humble number, please write a program to calculate the number of divisors about this humble number.For examle, 4 is a humble,and it have 3 divisors(1,2,4);12 have 6 divisors.

Input

The input consists of multiple test cases. Each test case consists of one humble number n,and n is in the range of 64-bits signed integer. Input is terminated by a value of zero for n.

Output

For each test case, output its divisor number, one line per case.

Sample Input

4
12
0

Sample Output

3
6

代码如下：

#include <cstdio>
#include <cstring>
int main()
{
    __int64 n;
    __int64 a[4] = {2,3,5,7}, b[4];
    while(scanf("%I64d",&n) && n)
    {
        memset(b,0,sizeof(b));
        for(int i = 0; i < 4; i++)
        {
            while(n%a[i] == 0)
            {
                b[i]++;
                n/=a[i];
            }
        }
        __int64 ans = (b[0]+1)*(b[1]+1)*(b[2]+1)*(b[3]+1);
        printf("%I64d\n",ans);
    }
    return 0;
}