Description
Given an integer n, return true if it is possible to represent n as the sum of distinct powers of three. Otherwise, return false.
An integer y is a power of three if there exists an integer x such that y == 3x.
Example 1:
Input: n = 12 Output: true Explanation: 12 = 31 + 32
Example 2:
Input: n = 91 Output: true Explanation: 91 = 30 + 32 + 34
Example 3:
Input: n = 21 Output: false
Constraints:
1 <= n <= 107
Solution
Python3
class Solution:
def checkPowersOfThree(self, n: int) -> bool:
# T(n) = T(n / 3) + O(1)
# = O(log n)
while n > 1:
if n % 3 == 2: return False
n //= 3
return n == 1