LeetCode 풀기 - 231. Power of Two

https://leetcode.com/problems/power-of-two/

Power of Two - LeetCode

문제)

솔루션1)

• 2의 승수는 A & (A-1) = 0을 만족
  • 예시) 16 -> 10000, 16-1 -> 01111, 16 & 15 -> 10000 & 01111 = 0

class Solution:
    def isPowerOfTwo(self, n: int) -> bool:
        if n == 0:
            return False 
        return (n & (n - 1)) == 0

솔루션2)

• 왼쪽 shift 연산자를 활용

class Solution:
    def isPowerOfTwo(self, n: int) -> bool:
        m = 1
        while m < n:
            m <<= 1
        return m == n

솔루션3)

• 오른쪽 shift 연산자를 활용

class Solution:
    def isPowerOfTwo(self, n: int) -> bool:
        count = 0
        while n > 0:
            count += n & 1
            if count > 1:
                return False
            n >>= 1
        return count == 1