476. Number Complement

Given a positive integer num, output its complement number. The complement strategy is to flip the bits of its binary representation.

 

Example 1:

Input: num = 5
Output: 2
Explanation: The binary representation of 5 is 101 (no leading zero bits), and its complement is 010. So you need to output 2.

Example 2:

Input: num = 1
Output: 0
Explanation: The binary representation of 1 is 1 (no leading zero bits), and its complement is 0. So you need to output 0.

 

Constraints:

Rust Solution

struct Solution;

impl Solution {
    fn find_complement(num: i32) -> i32 {
        let mut mask = !0;
        while mask & num != 0 {
            mask <<= 1;
        }
        !mask & !num
    }
}

#[test]
fn test() {
    assert_eq!(Solution::find_complement(5), 2);
    assert_eq!(Solution::find_complement(1), 0);
}

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