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
Companies:
Microsoft
Related Topics:
Math, Backtracking, Recursion
Similar Questions:
// OJ: https://leetcode.com/problems/check-if-number-is-a-sum-of-powers-of-three/
// Author: github.com/lzl124631x
// Time: O(log_3^N)
// Space: O(1)
class Solution {
public:
bool checkPowersOfThree(int n) {
while (n % 3 == 0 || (n % 3 == 1 && n != 1)) {
if (n % 3 == 1) n -= 1;
n /= 3;
}
return n == 1;
}
};