Ugly Number Problem & Solution

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.

See the ugly number problem on LeetCode.

C++ Solution

#pragma GCC optimize("Ofast")
#pragma GCC optimization("unroll-loops")

static const int _=[](){std::ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();

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

    while (n > 1 && n % 3 == 0) {
      n /= 3;
    }
    
    while (n > 1 && n % 5 == 0) {
      n /= 5;
    }
    
    return n == 1;
  }
};

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