题目

Write a program to check whether a given number is an ugly number.

Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 6, 8 are ugly while 14 is not ugly since it includes another prime factor 7.

Note that 1 is typically treated as an ugly number.

我的解法

public class Solution { public boolean isUgly(int num) { if(num == 0) return false; while(true){ if(num % 2 == 0) num = num/2; else if(num % 3 == 0) num = num/3; else if(num % 5 == 0) num = num/5; else break; } return num == 1; } }算法分析：若是脏数，则不断除2、除3、除5，最后一定得到1；否则就不是。