Description
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.
Examples:
Example 1:
Input: n = 6
Output: true
Explanation: 6 = 2 × 3
Example 2:
Input: n = 1
Output: true
Explanation: 1 has no prime factors, therefore all of its prime factors are limited to 2, 3, and 5.
Example 3:
Input: n = 14
Output: false
Explanation: 14 is not ugly since it includes the prime factor 7.Solution in Python
Python
class Solution:
def isUgly(self, n: int) -> bool:
# If the number is less than or equal to zero, it is not considered an ugly number
if n <= 0:
return False
# Continuously divide the number by 2, 3, or 5 if it's divisible by these numbers
for factor in [2, 3, 5]:
while n % factor == 0: # While the number is divisible by the current factor
n //= factor # Divide the number by the factor
# If after removing all 2s, 3s, and 5s, n is reduced to 1, it's an ugly number
return n == 1Explanation:
- Initial Check: We first check if
nis less than or equal to zero. If it is, the number cannot be ugly (since ugly numbers are positive integers), so we returnFalse. - Prime Factors (2, 3, 5): We then loop through the prime factors (2, 3, and 5). For each factor, we use a
whileloop to keep dividingnby that factor as long as it’s divisible. This removes all instances of 2, 3, and 5 fromn. - Final Check: After the loop finishes, if
nhas been reduced to 1, it means the original number only had 2, 3, and 5 as prime factors, so we returnTrue. Otherwise, we returnFalse.
Solution in C++
C++
class Solution {
public:
bool isUgly(int n) {
// If the number is less than or equal to zero, it is not considered an ugly number
if (n <= 0) {
return false;
}
// Continuously divide the number by 2, 3, or 5 if it's divisible by these numbers
for (int factor : {2, 3, 5}) {
while (n % factor == 0) { // While n is divisible by the current factor
n /= factor; // Divide n by the factor
}
}
// If after removing all 2s, 3s, and 5s, n is reduced to 1, it's an ugly number
return n == 1;
}
};Solution in Javascript
JavaScript
/**
* @param {number} n
* @return {boolean}
*/
var isUgly = function(n) {
// If the number is less than or equal to zero, it is not considered an ugly number
if (n <= 0) {
return false;
}
// Array of prime factors we want to check: 2, 3, and 5
const factors = [2, 3, 5];
// Iterate through each prime factor
for (let factor of factors) {
// While n is divisible by the current factor
while (n % factor === 0) {
n /= factor; // Divide n by the factor to remove that factor completely
}
}
// After removing all 2s, 3s, and 5s, if n is reduced to 1, it is an ugly number
return n === 1;
};Solution in Java
Java
class Solution {
public boolean isUgly(int n) {
// If the number is less than or equal to zero, it is not considered an ugly number
if (n <= 0) {
return false;
}
// Define an array of prime factors we want to check: 2, 3, and 5
int[] factors = {2, 3, 5};
// Iterate through each prime factor
for (int factor : factors) {
// While n is divisible by the current factor
while (n % factor == 0) {
n /= factor; // Divide n by the factor to remove that factor completely
}
}
// After removing all 2s, 3s, and 5s, if n is reduced to 1, it is an ugly number
return n == 1;
}
}