LeetCode Entry
231. Power of Two
Is number 2^x?
231. Power of Two easy
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Problem TLDR
Is number 2^x?
Intuition
Power of two number has just one bit on: 2 -> 10, 4 -> 100, 8 -> 1000.
There is a known bit trick to turn off a single rightmost bit: n & (n - 1).
Approach
- careful with the negative numbers and zero
Complexity
-
Time complexity: \(O(1)\)
-
Space complexity: \(O(1)\)
Code
fun isPowerOfTwo(n: Int) =
n > 0 && n and (n - 1) == 0
pub fn is_power_of_two(n: i32) -> bool {
n > 0 && n & (n - 1) == 0
}