Python100例--014

题目：将一个正整数分解质因数。例如：输入90,打印出90=233*5

# -*- coding: UTF-8 -*-
def reduceNum(n):
    print '{} = '.format(n),
    if not isinstance(n, int) or n <= 0:
        print '请输入一个正确的数字 !'
        exit(0)
    elif n in [1]:
        print '{}'.format(n)
    while n not in [1]:  # 循环保证递归
        for index in xrange(2, n + 1):
            if n % index == 0:
                n /= index  # n 等于 n/index
                if n == 1:
                    print index
                else:  # index 一定是素数
                    print '{} *'.format(index),
                break

reduceNum(90)
reduceNum(100)