Calculate Bitwise OR of two integers from their given Bitwise AND and Bitwise XOR values

Given two integers X and Y, representing Bitwise XOR and Bitwise AND of two positive integers, the task is to calculate the Bitwise OR value of those two positive integers.

Examples:

Input: X = 5, Y = 2 
Output: 7 
Explanation:
If A and B are two positive integers such that A ^ B = 5, A & B = 2, then the possible value of A and B is 3 and 6 respectively. 
Therefore, (A | B) = (3 | 6) = 7.

Input: X = 14, Y = 1 
Output: 15 
Explanation:
If A and B are two positive integers such that A ^ B = 14, A & B = 1, then the possible value of A and B is 7 and 9 respectively. 
Therefore, (A | B) = (7 | 9) = 15.

Naive Approach: The simplest approach to solve this problem is to iterate up to the maximum of X and Y, say N, and generate all possible pairs of the first N natural numbers. For each pair, check if Bitwise XOR and the Bitwise AND of the pair is X and Y, respectively, or not. If found to be true, then print the Bitwise OR of that pair.

Time Complexity: O(N²), where N = max(X, Y)
Auxiliary Space: O(1)

Efficient Approach: To optimize the above approach, the idea is based on the following observations:

(A ^ B) = (A | B) – (A & B) 
=> (A | B) = (A ^ B) + (A & B) = X + Y 

Below is the implementation of the above approach:

C++

// C++ program to implement
// the above approach

#include <bits/stdc++.h>
using namespace std;

// Function to calculate Bitwise OR from given
// bitwise XOR and bitwise AND values
int findBitwiseORGivenXORAND(int X, int Y) { return X + Y; }

// Driver Code
int main()
{
    int X = 5, Y = 2;
    cout << findBitwiseORGivenXORAND(X, Y);
}

C

// C program to implement
// the above approach
#include <stdio.h>

// Function to calculate Bitwise OR from given
// bitwise XOR and bitwise AND values
int findBitwiseORGivenXORAND(int X, int Y)
{
  return X + Y;
}

// Driver Code
int main()
{
    int X = 5, Y = 2;
    printf("%d\n", findBitwiseORGivenXORAND(X, Y));
}

// This code is contributed by phalashi.

Java

// Java program to implement
// the above approach
class GFG {

    // Function to calculate Bitwise OR from given
    // bitwise XOR and bitwise AND values
    static int findBitwiseORGivenXORAND(int X, int Y)
    {
        return X + Y;
    }

    // Driver Code
    public static void main(String[] args)
    {
        int X = 5, Y = 2;
        System.out.print(findBitwiseORGivenXORAND(X, Y));
    }
}

// This code is contributed by AnkitRai01

Python3

# Python3 program to implement
# the above approach

# Function to calculate Bitwise OR from
# given bitwise XOR and bitwise AND values


def findBitwiseORGivenXORAND(X, Y):

    return X + Y


# Driver Code
if __name__ == "__main__":

    X = 5
    Y = 2

    print(findBitwiseORGivenXORAND(X, Y))

# This code is contributed by AnkitRai01

C#

// C# program to implement
// the above approach
using System;

class GFG {

    // Function to calculate Bitwise OR from given
    // bitwise XOR and bitwise AND values
    static int findBitwiseORGivenXORAND(int X, int Y)
    {
        return X + Y;
    }

    // Driver Code
    public static void Main(string[] args)
    {
        int X = 5, Y = 2;

        Console.Write(findBitwiseORGivenXORAND(X, Y));
    }
}

// This code is contributed by ipg2016107

Javascript

<script>
// JavaScript program to implement
// the above approach

// Function to calculate Bitwise OR from given
// bitwise XOR and bitwise AND values
function findBitwiseORGivenXORAND(X, Y)
{
    return X + Y;
}

// Driver Code

    let X = 5, Y = 2;
    document.write(findBitwiseORGivenXORAND(X, Y));

// This code is contributed by Surbhi Tyagi.

</script>

Output:

7

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