Find One’s Complement of an Integer | Set 2

Given an integer N, find the one’s complement of the integer.

Examples:

Input: N = 5
Output: 2
Explanation: Binary representation of 5 is “101”. Its one’s complement is “010” = 2.

Input: N = 255
Output: 0

Input: N = 26
Output: 5

Approach: Already the XOR-based approach and converting the number to binary number approaches are mentioned in Set-1 of the article. Here the number is converted by flipping bits and adding that power of 2 to the answer. Follow the steps mentioned below to implement it:

• Find the binary representation of N.
• For each bit, complement it and add the contribution of this bit to the final answer.
• Return the final answer

Below is the implementation of the above approach.

C++

// CPP program to find 1's complement of N.
#include <bits/stdc++.h>
using namespace std;

// Find the 1's complement of N
int findComplement(int num)
{
    int ans = 0;
    for (int i = 0; num > 0; i++) {
        ans += pow(2, i) * (!(num % 2));
        num /= 2;
    }

    return ans;
}

// Driver code
int main()
{
    unsigned int N = 5;
    cout << findComplement(N);
    return 0;
}

Java

// Java code for the above approach
import java.util.*;
public class GFG
{

  // Find the 1's complement of N
  static int findComplement(int num)
  {
    int ans = 0;
    for (int i = 0; num > 0; i++) {
      if(num % 2 == 0) {
        ans += (int)Math.pow(2, i) ;
      }
      num /= 2;
    }

    return ans;
  }

  // Driver code
  public static void main(String args[])
  {
    Integer N = 5;
    System.out.println(findComplement((int)N));
  }
}

// This code is contributed by Samim Hossain Mondal

Python3

# python3 program to find 1's complement of N.

# Find the 1's complement of N
def findComplement(num):

    ans = 0
    i = 0
    while(True):
        if num == 0:
            break
        ans += pow(2, i) * (not (num % 2))
        num //= 2
        i += 1

    return ans

# Driver code
if __name__ == "__main__":

    N = 5
    print(findComplement(N))

# This code is contributed by rakeshsahni

C#

// C# code for the above approach
using System;
class GFG
{

// Find the 1's complement of N
static int findComplement(int num)
{
    int ans = 0;
    for (int i = 0; num > 0; i++) {
        if(num % 2 == 0) {
            ans += (int)Math.Pow(2, i) ;
        }
        num /= 2;
    }

    return ans;
}

// Driver code
public static void Main()
{
    uint N = 5;
    Console.Write(findComplement((int)N));
}
}

// This code is contributed by Samim Hossain Mondal

Javascript

<script>
      // JavaScript code for the above approach


      // Find the 1's complement of N
      function findComplement(num) {
          let ans = 0;
          for (let i = 0; num > 0; i++) {
              ans += Math.pow(2, i) * (!(num % 2));
              num = Math.floor(num / 2);
          }

          return ans;
      }

      // Driver code

      let N = 5;
      document.write(findComplement(N));


// This code is contributed by Potta Lokesh
  </script>

Output

2

Time Complexity: O(log N)
Auxiliary Space: O(1)