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# Count pairs from given array with Bitwise OR equal to K

• Last Updated : 23 Apr, 2021

Given an array arr[] consisting of N positive integers and an integer K, the task is to count all pairs possible from the given array with Bitwise OR equal to K.

Examples:

Input: arr[] = {2, 38, 44, 29, 62}, K = 46
Output: 2
Explanation: Only the following two pairs are present in the array whose Bitwise OR is 46:

• 2 OR 44 = 46
• 38 OR 44 = 46

Input: arr[] = {1, 5, 20, 15, 14}, K = 20
Output: 5
Explanation:
There are only 5 pairs whose Bitwise OR is 20:

• 1 OR 15 = 15
• 1 OR 14 = 15
• 5 OR 15 = 15
• 5 OR 14 = 15
• 15 OR 14 = 15

Approach: To solve the problem, the idea is to generate all possible pairs from the given array and count those pairs whose Bitwise OR is equal to K. After checking for all the pairs, print the count stored.

Below is the implementation of the above approach:

## C++

 `// C++ program for the above approach``#include ``using` `namespace` `std;` `// Function that counts the pairs from``// the array whose Bitwise OR is K``void` `countPairs(``int` `arr[], ``int` `k, ``int` `size)``{``    ``// Stores the required``    ``// count of pairs``    ``int` `count = 0, x;` `    ``// Generate all possible pairs``    ``for` `(``int` `i = 0; i < size - 1; i++) {` `        ``for` `(``int` `j = i + 1; j < size; j++) {` `            ``// Perform OR operation``            ``x = arr[i] | arr[j];` `            ``// If Bitwise OR is equal``            ``// to K, increment count``            ``if` `(x == k)``                ``count++;``        ``}``    ``}` `    ``// Print the total count``    ``cout << count;``}` `// Driver Code``int` `main()``{``    ``int` `arr[] = { 2, 38, 44, 29, 62 };``    ``int` `K = 46;``    ``int` `N = ``sizeof``(arr) / ``sizeof``(arr);` `    ``// Function Call``    ``countPairs(arr, K, N);` `    ``return` `0;``}`

## Java

 `// Java program for the above approach``import` `java.io.*;``import` `java.util.*;`` ` `class` `GFG{`` ` `// Function that counts the pairs from``// the array whose Bitwise OR is K``static` `void` `countPairs(``int``[] arr, ``int` `k,``                       ``int` `size)``{``    ` `    ``// Stores the required``    ``// count of pairs``    ``int` `count = ``0``, x;`` ` `    ``// Generate all possible pairs``    ``for``(``int` `i = ``0``; i < size - ``1``; i++)``    ``{``        ``for``(``int` `j = i + ``1``; j < size; j++)``        ``{``            ` `            ``// Perform OR operation``            ``x = arr[i] | arr[j];`` ` `            ``// If Bitwise OR is equal``            ``// to K, increment count``            ``if` `(x == k)``                ``count++;``        ``}``    ``}`` ` `    ``// Print the total count``    ``System.out.println(count);``}`` ` `// Driver Code``public` `static` `void` `main(String[] args)``{``    ``int``[] arr = { ``2``, ``38``, ``44``, ``29``, ``62` `};``    ``int` `K = ``46``;``    ``int` `N = arr.length;`` ` `    ``// Function Call``    ``countPairs(arr, K, N);``}``}`` ` `// This code is contributed by code_hunt`

## Python3

 `# Python3 program for the above approach`` ` `# Function that counts the pairs from``# the array whose Bitwise OR is K``def` `countPairs(arr, k, size):``    ` `    ``# Stores the required``    ``# count of pairs``    ``count ``=` `0`` ` `    ``# Generate all possible pairs``    ``for` `i ``in` `range``(size ``-` `1``):``        ``for` `j ``in` `range``(i ``+` `1``, size):``            ` `            ``# Perform OR operation``            ``x ``=` `arr[i] | arr[j]`` ` `            ``# If Bitwise OR is equal``            ``# to K, increment count``            ``if` `(x ``=``=` `k):``                ``count ``+``=` `1`` ` `    ``# Print the total count``    ``print``(count)` `# Driver Code``arr ``=` `[ ``2``, ``38``, ``44``, ``29``, ``62` `]``K ``=` `46``N ``=` `len``(arr)`` ` `# Function Call``countPairs(arr, K, N)` `# This code is contributed by sanjoy_62`

## C#

 `// C# program for the above approach``using` `System;``  ` `class` `GFG{``  ` `// Function that counts the pairs from``// the array whose Bitwise OR is K``static` `void` `countPairs(``int``[] arr, ``int` `k,``                       ``int` `size)``{``    ` `    ``// Stores the required``    ``// count of pairs``    ``int` `count = 0, x;``  ` `    ``// Generate all possible pairs``    ``for``(``int` `i = 0; i < size - 1; i++)``    ``{``        ``for``(``int` `j = i + 1; j < size; j++)``        ``{``            ` `            ``// Perform OR operation``            ``x = arr[i] | arr[j];``            ` `            ``// If Bitwise OR is equal``            ``// to K, increment count``            ``if` `(x == k)``                ``count++;``        ``}``    ``}``    ` `    ``// Print the total count``    ``Console.WriteLine(count);``}``  ` `// Driver Code``public` `static` `void` `Main()``{``    ``int``[] arr = { 2, 38, 44, 29, 62 };``    ``int` `K = 46;``    ``int` `N = arr.Length;``    ` `    ``// Function Call``    ``countPairs(arr, K, N);``}``}``  ` `// This code is contributed by susmitakundugoaldanga`

## Javascript

 ``
Output:
`2`

Time Complexity: O(N2)
Auxiliary Space: O(1)

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