leetcode Number Complement

476. Number Complement

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

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.

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.

import java.util.*;

public class Solution {
public static int findComplement(int num) {
   int comp = 0;
   int i = 0;
        while(num != 0){
            int a = num % 2;
            int b = num / 2;
            num = b;
            comp += ((a+1)%2)*Math.pow(2, i);
            i++;
        }
        return comp;
}
public static void main(String args[]){
Scanner reader = new Scanner(System.in);
try{
int num = reader.nextInt();
if(num>=0){
System.out.print(findComplement(num));
}
}catch(Exception e){
System.out.print("wrong");
}

}
}