Leetcode skimming ---263

subject ： Ugly number   That is, only the prime factor is included  2、3  and  5  The positive integer . Give you an integer  n , Please judge  n  Is it   Ugly number  . If it is , return  true ; otherwise , return  false .

Input ：n = 6

Output ：true

Method 1 ： mathematics

class Solution {
public:
    bool isUgly(int n) {
        if (n <=0 ) {
            return false;
        } 
        vector<int> factors = {2, 3, 5};
        for (int factor: factors) {
            while (n % factor == 0) {
                n /= factor;
            }
        }
        return n == 1;
    }
};

Complexity analysis

Time complexity ：O(logn)

Spatial complexity ：O(1)