Given an integer n, return true if it is a power of four. Otherwise, return false.
An integer n is a power of four, if there exists an integer x such that n == 4x.
Example 1:
Input: n = 16 Output: true
Example 2:
Input: n = 5 Output: false
Example 3:
Input: n = 1 Output: true
Constraints:
-231 <= n <= 231 - 1Follow up: Could you solve it without loops/recursion?
struct Solution;
use std::i32;
impl Solution {
fn is_power_of_four(mut n: i32) -> bool {
while n != 0 && n % 4 == 0 {
n /= 4;
}
n == 1
}
}
#[test]
fn test() {
assert_eq!(Solution::is_power_of_four(16), true);
}