[LeetCode]263. Ugly Number

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.

1. 将该数一直除以2/3/5，看最后是不是1

class Solution {public:    bool isUgly(int num) {        if (num <=0) return false;        while (num >1)        {            if (num %2 == 0) num /= 2;            else if (num %3 == 0) num /= 3;            else if (num %5 == 0) num /= 5;            else return 0;        }        return num == 1;    }};

2.solution里的的办法

bool isUgly(int num) {    int i;    for (i=2;i<=5&&num>0;i++)    {        while(num%i==0) num/= i;    }    return num==1;}