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Calculate Bitwise OR of two integers from their given Bitwise AND and Bitwise XOR values
• Difficulty Level : Basic
• Last Updated : 04 Mar, 2021

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:
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 ``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);``}`

## 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

 ``
Output:
`7`

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

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