Question

326. Power of Three

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Description

Given an integer n, return _true if it is a power of three. Otherwise, return false_.

An integer n is a power of three, if there exists an integer x such that n == 3x.

 

Example 1:

Input: n = 27
Output: true
Explanation: 27 = 33

Example 2:

Input: n = 0
Output: false
Explanation: There is no x where 3x = 0.

Example 3:

Input: n = -1
Output: false
Explanation: There is no x where 3x = (-1).

 

Constraints:

• -231 <= n <= 231 - 1

 

Follow up: Could you solve it without loops/recursion?

Solutions

Solution 1

class Solution:
  def isPowerOfThree(self, n: int) -> bool:
    while n > 2:
      if n % 3:
        return False
      n //= 3
    return n == 1

class Solution {
  public boolean isPowerOfThree(int n) {
    while (n > 2) {
      if (n % 3 != 0) {
        return false;
      }
      n /= 3;
    }
    return n == 1;
  }
}

class Solution {
public:
  bool isPowerOfThree(int n) {
    while (n > 2) {
      if (n % 3) {
        return false;
      }
      n /= 3;
    }
    return n == 1;
  }
};

func isPowerOfThree(n int) bool {
  for n > 2 {
    if n%3 != 0 {
      return false
    }
    n /= 3
  }
  return n == 1
}

function isPowerOfThree(n: number): boolean {
  return n > 0 && 1162261467 % n == 0;
}

/**
 * @param {number} n
 * @return {boolean}
 */
var isPowerOfThree = function (n) {
  return n > 0 && 1162261467 % n == 0;
};

Solution 2

class Solution:
  def isPowerOfThree(self, n: int) -> bool:
    return n > 0 and 1162261467 % n == 0

class Solution {
  public boolean isPowerOfThree(int n) {
    return n > 0 && 1162261467 % n == 0;
  }
}

class Solution {
public:
  bool isPowerOfThree(int n) {
    return n > 0 && 1162261467 % n == 0;
  }
};

func isPowerOfThree(n int) bool {
  return n > 0 && 1162261467%n == 0
}