Complement of Base 10 Integer - LeetCode solutions

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 n, return its complement.

Example 1:

Input: n = 5
Output: 2
Explanation: 5 is "101" in binary, with complement "010" in binary, which is 2 in base-10.

Example 2:

Input: n = 7
Output: 0
Explanation: 7 is "111" in binary, with complement "000" in binary, which is 0 in base-10.

Example 3:

Input: n = 10
Output: 5
Explanation: 10 is "1010" in binary, with complement "0101" in binary, which is 5 in base-10.

Constraints:

0 <= n < 10^9

Note: This question is the same as 476: https://leetcode.com/problems/number-complement/

Solution (Java)

class Solution {
    public int bitwiseComplement(int n) {
        if (n == 0) {
            return 1;
        }
        List<Integer> list = new ArrayList<>();
        while (n != 0) {
            list.add(n & 1);
            n >>= 1;
        }
        int result = 0;
        int exp = list.size() - 1;
        for (int i = list.size() - 1; i >= 0; i--) {
            if (list.get(i) == 0) {
                result += Math.pow(2, exp);
            }
            exp--;
        }
        return result;
    }
}

Explain:

nope.

Complexity:

Time complexity : O(n).
Space complexity : O(n).