Question

263. Ugly Number

中文文档

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_.

 

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.

 

Constraints:

• -231 <= n <= 231 - 1

Solutions

Solution 1

class Solution:
  def isUgly(self, n: int) -> bool:
    if n < 1:
      return False
    for x in [2, 3, 5]:
      while n % x == 0:
        n //= x
    return n == 1

class Solution {
  public boolean isUgly(int n) {
    if (n < 1) return false;
    while (n % 2 == 0) {
      n /= 2;
    }
    while (n % 3 == 0) {
      n /= 3;
    }
    while (n % 5 == 0) {
      n /= 5;
    }
    return n == 1;
  }
}

class Solution {
public:
  bool isUgly(int n) {
    if (n < 1) return false;
    while (n % 2 == 0) {
      n /= 2;
    }
    while (n % 3 == 0) {
      n /= 3;
    }
    while (n % 5 == 0) {
      n /= 5;
    }
    return n == 1;
  }
};

func isUgly(n int) bool {
  if n < 1 {
    return false
  }
  for _, x := range []int{2, 3, 5} {
    for n%x == 0 {
      n /= x
    }
  }
  return n == 1
}

/**
 * @param {number} n
 * @return {boolean}
 */
var isUgly = function (n) {
  if (n < 1) return false;
  while (n % 2 === 0) {
    n /= 2;
  }
  while (n % 3 === 0) {
    n /= 3;
  }
  while (n % 5 === 0) {
    n /= 5;
  }
  return n === 1;
};

class Solution {
  /**
   * @param Integer $n
   * @return Boolean
   */
  function isUgly($n) {
    while ($n) {
      if ($n % 2 == 0) {
        $n = $n / 2;
      } elseif ($n % 3 == 0) {
        $n = $n / 3;
      } elseif ($n % 5 == 0) {
        $n = $n / 5;
      } else {
        break;
      }
    }
    return $n == 1;
  }
}