476. Number Complement

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Problem

The complement of an integer is the integer you get when you flip all the 0’s to 1’s and all the 1’s to 0’s in its binary representation.

• For example, The integer 5 is “101” in binary and its complement is “010” which is the integer 2. Given an integer num, return its complement.

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:

• 1 <= num < 2^31

Code

重复题目 1009

class Solution {
    public int bitwiseComplement(int n) {
        if(n == 0) return 1;
        
        int temp = n;
        int mask = 1;
      
        while (temp != 0) {
            n = n ^ mask;

            mask <<= 1;
            temp >>= 1;
        }
        
        return n;
    }
}