Ugly Number

• LeetCode: Ugly Number

• Problem:

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.

• Note:

Note that 1 is typically treated as an ugly number.

• Examples:

For example, 6, 8 are ugly while 14 is not ugly since it includes another prime factor 7.

• Analysis:

An ugly number is that its prime factors are only 2, 3, 5.

• Code - Java:

class Solution {
    public boolean isUgly(int num) {
        while (num > 0 && num % 2 == 0) {
            num /= 2;
        }
        while (num > 0 && num % 3 == 0) {
            num /= 3;
        }
        while (num > 0 && num % 5 == 0) {
            num /= 5;
        }
        return num == 1;
    }
}

• Code - C++:

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

• Code - Python:

class Solution(object):
    def isUgly(self, num):
        """
        :type num: int
        :rtype: bool
        """
        while num > 0 and num % 2 == 0:
            num /= 2
        while num > 0 and num % 3 == 0:
            num /= 3
        while num > 0 and num % 5 == 0:
            num /= 5
        return num == 1

• Code - C:

bool isUgly(int num) {
    while (num > 0 && num % 2 == 0) {
        num /= 2;
    }
    while (num > 0 && num % 3 == 0) {
        num /= 3;
    }
    while (num > 0 && num % 5 == 0) {
        num /= 5;
    }
    return num == 1;    
}