Question
Formatted question description: https://leetcode.ca/all/263.html
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.
Example 1:
Input: 6
Output: true
Explanation: 6 = 2 × 3
Example 2:
Input: 8
Output: true
Explanation: 8 = 2 × 2 × 2
Example 3:
Input: 14
Output: false
Explanation: 14 is not ugly since it includes another prime factor 7.
Note:
1 is typically treated as an ugly number.
Input is within the 32-bit signed integer range: [−231, 231 − 1].
@tag-heap
Algorithm
Keep being devided by these prime numbers, if the remaining number is 1, it is an ugly number.
Code
Java
public class Ugly_Number {
class Solution {
public boolean isUgly(int num) {
if(num == 0) {
return false;
}
while( num % 2 == 0) {
num /=2;
}
while( num % 3 == 0) {
num /=3;
}
while( num % 5 == 0) {
num /=5;
}
return num == 1;
}
}
}