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Count pairs from given array with Bitwise OR equal to K

  • Last Updated : 23 Apr, 2021
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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 <iostream>
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[0]);
 
    // 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




<script>
// JavaScript program for the above approach
 
// Function that counts the pairs from
// the array whose Bitwise OR is K
function countPairs(arr, k, size)
{
      
    // Stores the required
    // count of pairs
    let count = 0, x;
   
    // Generate all possible pairs
    for(let i = 0; i < size - 1; i++)
    {
        for(let 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++;
        }
    }
   
    // Prlet the total count
    document.write(count);
}
  
// Driver Code
       let arr = [ 2, 38, 44, 29, 62 ];
    let K = 46;
    let N = arr.length;
   
    // Function Call
    countPairs(arr, K, N);
    
   // This code is contributed by avijitmondal998.
</script>
Output: 
2

 

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

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