Ugly Number

LeetCode Q 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.

Solution

Code: Recursive approach

public boolean isUgly(int n) {
	if (n <= 0) return false;
	else if (n == 1 || n == 2 || n == 3 || n == 5) return true;
	else if (n % 2 == 0) return isUgly(n / 2);
	else if (n % 3 == 0) return isUgly(n / 3);
	else if (n % 5 == 0) return isUgly(n / 5);
	else return false;
}

Code: Iterative approach

public boolean isUgly(int n) {
	if (n <= 0) return false;
	
	while (n >= 2 && n % 2 == 0) n /= 2;
	while (n >= 3 && n % 3 == 0) n /= 3; 
	while (n >= 5 && n % 5 == 0) n /= 5;

	return n == 1;
}