Number Complement - Leetcode May 30-Day Challenge

Number Complement.md

Number Complement

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

Example 1:

Input: 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: 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.

Note:

1. The given integer is guaranteed to fit within the range of a 32-bit signed integer.
2. You could assume no leading zero bit in the integer’s binary representation.
3. This question is the same as 1009: https://leetcode.com/problems/complement-of-base-10-integer/

Solution.java

class Solution {
    public int findComplement(int num) {
        String bits = Long.toBinaryString((long)num);
        System.out.println(bits);
        StringBuilder sb = new StringBuilder();
        for(int i = 0; i < bits.length(); i++) {
            if(bits.charAt(i) == '0') {
                sb.append('1');
            } else {
                sb.append('0');
            }
        }
        return Integer.parseInt(sb.toString(), 2);
    }
}