Ugly Number Problem


Description

LeetCode Problem 263.

An ugly number is a positive integer whose prime factors are limited to 2, 3, and 5.

Given an integer n, return true if n is an ugly number.

Example 1:

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Input: n = 6
Output: true
Explanation: 6 = 2 × 3

Example 2:

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Input: n = 8
Output: true
Explanation: 8 = 2 × 2 × 2

Example 3:

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Input: n = 14
Output: false
Explanation: 14 is not ugly since it includes the prime factor 7.

Example 4:

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Input: n = 1
Output: true
Explanation: 1 has no prime factors, therefore all of its prime factors are limited to 2, 3, and 5.

Constraints:

  • -2^31 <= n <= 2^31 - 1


Sample C++ Code

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class Solution {
public:
    bool isUgly(int num) {
        if (num == 1)
            return true;
        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 false;
        }
        return true;
    }
};




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