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# Find a K-length subarray having Bitwise XOR equal to that of remaining array elements

• Difficulty Level : Easy
• Last Updated : 30 Apr, 2021

Given an array arr[] of size N, the task is to check if any subarray of size K exists in the array or not, whose Bitwise XOR is equal to the Bitwise XOR of the remaining array elements. If found to be true, then print “YES”. Otherwise, print “NO”.

Examples:

Input: arr[] = { 2, 3, 3, 5, 7, 7, 3, 4 }, K = 5
Output: YES
Explanation:
Bitwise XOR of the subarray { 3, 3, 5, 7, 7 } is equal to 5
Bitwise XOR of { 2, 3, 4 } is equal to 5.
Therefore, the required output is YES.

Input: arr[] = { 2, 3, 4, 5, 6, 7, 4 }, K = 2
Output: NO

Naive Approach: The simplest approach to solve this problem is to generate all subarrays of size K. For each subarray, check if the bitwise XOR of the subarray is equal to bitwise XOR of remaining elements or not. If found to be true, then print “YES”. Otherwise, print “NO”

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

Efficient Approach: The above approach can be optimized using Sliding Window Technique Following are the observations:

If X ^ Y = Z, then X ^ Z = Y
SubarrayXOR = arr[i] ^ arr[i + 1] ^ … ^ arr[j]
totalXOR = arr[0] ^ arr[1] ^ arr[2] ….. ^ arr[N – 1]
Bitwise XOR of the remaining array elements = totalXOR ^ SubarrayXOR

• Calculate the Bitwise XOR of all array elements, say totalXOR.
• Calculate the Bitwise XOR of first K elements of the array, say SubarrayXOR.
• Use sliding window technique, traverse each subarray of size K and check if Bitwise XOR of the subarray is equal to the Bitwise XOR of the remaining array elements or not. If found to be true, then print “YES”.
• Otherwise, print “NO”.

Below is the implementation of the above approach:

## C++

 `// C++ program to implement``// the above approach` `#include ``using` `namespace` `std;` `// Utility function to check if subarray``// of size K exits whose XOR of elements``// equal to XOR ofremaning array elements``bool` `isSubarrayExistUtil(``int` `arr[], ``int` `K, ``int` `N)``{` `    ``int` `totalXOR = 0;``    ``int` `SubarrayXOR = 0;` `    ``// Find XOR of whole array``    ``for` `(``int` `i = 0; i < N; i++)``        ``totalXOR ^= arr[i];` `    ``// Find XOR of first K elements``    ``for` `(``int` `i = 0; i < K; i++)``        ``SubarrayXOR ^= arr[i];``    ``if` `(SubarrayXOR == (totalXOR ^ SubarrayXOR))``        ``return` `true``;` `    ``for` `(``int` `i = K; i < N; i++) {` `        ``// Adding XOR of next element``        ``SubarrayXOR ^= arr[i];` `        ``// Removing XOR of previous element``        ``SubarrayXOR ^= arr[i - 1];` `        ``// Check if XOR of current subarray matches``        ``// with the XOR of remaining elements or not``        ``if` `(SubarrayXOR == (totalXOR ^ SubarrayXOR))``            ``return` `true``;``    ``}``    ``return` `false``;``}` `// Function to check if subarray of size``// K exits whose XOR of elements equal``// to XOR ofremaning array elements``void` `isSubarrayExist(``int` `arr[], ``int` `K, ``int` `N)``{``    ``if` `(isSubarrayExistUtil(arr, K, N))``        ``cout << ``"YES\n"``;``    ``else``        ``cout << ``"NO\n"``;``}` `// Driver Code``int32_t main()``{``    ``// Given array``    ``int` `arr[] = { 2, 3, 3, 5, 7, 7, 3, 4 };` `    ``// Size of the array``    ``int` `N = ``sizeof``(arr) / ``sizeof``(arr[0]);` `    ``// Given K``    ``int` `K = 5;` `    ``// Function Call``    ``isSubarrayExist(arr, K, N);``}`

## Java

 `// Java program to implement``// the above approach``import` `java.util.*;` `class` `GFG{` `// Utility function to check if subarray``// of size K exits whose XOR of elements``// equal to XOR ofremaning array elements``static` `boolean` `isSubarrayExistUtil(``int` `arr[],``                                   ``int` `K, ``int` `N)``{``    ``int` `totalXOR = ``0``;``    ``int` `SubarrayXOR = ``0``;` `    ``// Find XOR of whole array``    ``for``(``int` `i = ``0``; i < N; i++)``        ``totalXOR ^= arr[i];` `    ``// Find XOR of first K elements``    ``for``(``int` `i = ``0``; i < K; i++)``        ``SubarrayXOR ^= arr[i];``    ``if` `(SubarrayXOR == (totalXOR ^ SubarrayXOR))``        ``return` `true``;` `    ``for``(``int` `i = K; i < N; i++)``    ``{``        ` `        ``// Adding XOR of next element``        ``SubarrayXOR ^= arr[i];` `        ``// Removing XOR of previous element``        ``SubarrayXOR ^= arr[i - ``1``];` `        ``// Check if XOR of current subarray matches``        ``// with the XOR of remaining elements or not``        ``if` `(SubarrayXOR == (totalXOR ^ SubarrayXOR))``            ``return` `true``;``    ``}``    ``return` `false``;``}` `// Function to check if subarray of size``// K exits whose XOR of elements equal``// to XOR ofremaning array elements``static` `void` `isSubarrayExist(``int` `arr[],``                            ``int` `K, ``int` `N)``{``    ``if` `(isSubarrayExistUtil(arr, K, N))``        ``System.out.print(``"YES\n"``);``    ``else``        ``System.out.print(``"NO\n"``);``}` `// Driver Code``public` `static` `void` `main(String[] args)``{``    ` `    ``// Given array``    ``int` `arr[] = { ``2``, ``3``, ``3``, ``5``, ``7``, ``7``, ``3``, ``4` `};` `    ``// Size of the array``    ``int` `N = arr.length;` `    ``// Given K``    ``int` `K = ``5``;` `    ``// Function Call``    ``isSubarrayExist(arr, K, N);``}``}` `// This code is contributed by 29AjayKumar`

## Python3

 `# Python3 program to implement``# the above approach` `# Utility function to check if subarray``# of size K exits whose XOR of elements``# equal to XOR ofremaning array elements``def` `isSubarrayExistUtil(arr, K, N):``    ``totalXOR ``=` `0``    ``SubarrayXOR ``=` `0` `    ``# Find XOR of whole array``    ``for` `i ``in` `range``(N):``        ``totalXOR ^``=` `arr[i]` `    ``# Find XOR of first K elements``    ``for` `i ``in` `range``(K):``        ``SubarrayXOR ^``=` `arr[i]``    ``if` `(SubarrayXOR ``=``=` `(totalXOR ^ SubarrayXOR)):``        ``return` `True` `    ``for` `i ``in` `range``(K, N):` `        ``# Adding XOR of next element``        ``SubarrayXOR ^``=` `arr[i]` `        ``# Removing XOR of previous element``        ``SubarrayXOR ^``=` `arr[i ``-` `1``]` `        ``# Check if XOR of current subarray matches``        ``# with the XOR of remaining elements or not``        ``if` `(SubarrayXOR ``=``=` `(totalXOR ^ SubarrayXOR)):``            ``return` `True``    ``return` `False` `# Function to check if subarray of size``# K exits whose XOR of elements equal``# to XOR ofremaning array elements``def` `isSubarrayExist(arr, K, N):``    ``if` `(isSubarrayExistUtil(arr, K, N)):``        ``print``(``"YES"``)``    ``else``:``        ``print``(``"NO"``)` `# Driver Code``if` `__name__ ``=``=` `'__main__'``:``    ` `    ``# Given array``    ``arr ``=` `[``2``, ``3``, ``3``, ``5``, ``7``, ``7``, ``3``, ``4``]` `    ``# Size of the array``    ``N ``=` `len``(arr)` `    ``# Given K``    ``K ``=` `5` `    ``# Function Call``    ``isSubarrayExist(arr, K, N)` `    ``# This code is contributed by mohit kumar 29`

## C#

 `// C# program to implement``// the above approach``using` `System;``class` `GFG``{` `// Utility function to check if subarray``// of size K exits whose XOR of elements``// equal to XOR ofremaning array elements``static` `bool` `isSubarrayExistUtil(``int` `[]arr,``                                   ``int` `K, ``int` `N)``{``    ``int` `totalXOR = 0;``    ``int` `SubarrayXOR = 0;` `    ``// Find XOR of whole array``    ``for``(``int` `i = 0; i < N; i++)``        ``totalXOR ^= arr[i];` `    ``// Find XOR of first K elements``    ``for``(``int` `i = 0; i < K; i++)``        ``SubarrayXOR ^= arr[i];``    ``if` `(SubarrayXOR == (totalXOR ^ SubarrayXOR))``        ``return` `true``;``    ``for``(``int` `i = K; i < N; i++)``    ``{``        ` `        ``// Adding XOR of next element``        ``SubarrayXOR ^= arr[i];` `        ``// Removing XOR of previous element``        ``SubarrayXOR ^= arr[i - 1];` `        ``// Check if XOR of current subarray matches``        ``// with the XOR of remaining elements or not``        ``if` `(SubarrayXOR == (totalXOR ^ SubarrayXOR))``            ``return` `true``;``    ``}``    ``return` `false``;``}` `// Function to check if subarray of size``// K exits whose XOR of elements equal``// to XOR ofremaning array elements``static` `void` `isSubarrayExist(``int` `[]arr,``                            ``int` `K, ``int` `N)``{``    ``if` `(isSubarrayExistUtil(arr, K, N))``        ``Console.Write(``"YES\n"``);``    ``else``        ``Console.Write(``"NO\n"``);``}` `// Driver Code``public` `static` `void` `Main(String[] args)``{``    ` `    ``// Given array``    ``int` `[]arr = { 2, 3, 3, 5, 7, 7, 3, 4 };` `    ``// Size of the array``    ``int` `N = arr.Length;` `    ``// Given K``    ``int` `K = 5;` `    ``// Function Call``    ``isSubarrayExist(arr, K, N);``}``}` `// This code is contributed by 29AjayKumar`

## Javascript

 ``
Output:
`YES`

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

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