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Minimize Bitwise XOR of array elements with 1 required to make sum of array at least K
• Last Updated : 18 May, 2021

Given an array arr[] consisting of N positive integers and a positive integer K, the task is to count minimum Bitwise XOR of array elements with 1 required such that the sum of the array is at least K.

Examples:

Input: arr[] = {0, 1, 1, 0, 1}, K = 4
Output: 1
Explanation: Performing Bitwise XOR of arr and 1 modifies arr[] to {1, 1, 1, 0, 1}. Now, the sum of array = 1 + 1 + 1 + 0 + 1 = 4(= K).

Input: arr[] = {14, 0, 1, 0}, K = 20
Output: -1

Approach: The given problem can be solved using the fact that Bitwise XOR of 1 with an even element increases the element by 1
Follow the steps below to solve the problem:

Below is the implementation of the above approach:

## C++

 `// C++ program for the above approach` `#include ``using` `namespace` `std;` `// Function to find minimum number``// of Bitwise XOR of array elements``// with 1 required to make sum of``// the array at least K``int` `minStepK(``int` `arr[], ``int` `N, ``int` `K)``{``    ``// Stores the count of``    ``// even array elements``    ``int` `E = 0;` `    ``// Stores sum of the array``    ``int` `S = 0;` `    ``// Traverse the array arr[]``    ``for` `(``int` `i = 0; i < N; i++) {` `        ``// Increment sum``        ``S += arr[i];` `        ``// If array element is even``        ``if` `(arr[i] % 2 == 0)` `            ``// Increase count of even``            ``E += 1;``    ``}` `    ``// If S is at least K``    ``if` `(S >= K)``        ``return` `0;` `    ``// If S + E is less than K``    ``else` `if` `(S + E < K)``        ``return` `-1;` `    ``// Otherwise, moves = K - S``    ``else``        ``return` `K - S;``}` `// Driver Code``int` `main()``{``    ``int` `arr[] = { 0, 1, 1, 0, 1 };``    ``int` `N = ``sizeof``(arr) / ``sizeof``(arr);``    ``int` `K = 4;``    ``cout << minStepK(arr, N, K);` `    ``return` `0;``}`

## Java

 `// Java program for the above approach``import` `java.util.*;` `class` `GFG{``    ` `// Function to find minimum number``// of Bitwise XOR of array elements``// with 1 required to make sum of``// the array at least K``static` `int` `minStepK(``int` `arr[], ``int` `N, ``int` `K)``{``    ` `    ``// Stores the count of``    ``// even array elements``    ``int` `E = ``0``;` `    ``// Stores sum of the array``    ``int` `S = ``0``;` `    ``// Traverse the array arr[]``    ``for``(``int` `i = ``0``; i < N; i++)``    ``{``        ` `        ``// Increment sum``        ``S += arr[i];` `        ``// If array element is even``        ``if` `(arr[i] % ``2` `== ``0``)` `            ``// Increase count of even``            ``E += ``1``;``    ``}` `    ``// If S is at least K``    ``if` `(S >= K)``        ``return` `0``;` `    ``// If S + E is less than K``    ``else` `if` `(S + E < K)``        ``return` `-``1``;` `    ``// Otherwise, moves = K - S``    ``else``        ``return` `K - S;``}` `// Driver code``public` `static` `void` `main(String[] args)``{``    ``int` `arr[] = { ``0``, ``1``, ``1``, ``0``, ``1` `};``    ``int` `N = arr.length;``    ``int` `K = ``4``;``    ` `    ``System.out.println(minStepK(arr, N, K));``}``}` `// This code is contributed by offbeat`

## Python3

 `# Python 3 program for the above approach` `# Function to find minimum number``# of Bitwise XOR of array elements``# with 1 required to make sum of``# the array at least K``def` `minStepK(arr, N, K):` `    ``# Stores the count of``    ``# even array elements``    ``E ``=` `0` `    ``# Stores sum of the array``    ``S ``=` `0` `    ``# Traverse the array arr[]``    ``for` `i ``in` `range``(N):` `        ``# Increment sum``        ``S ``+``=` `arr[i]` `        ``# If array element is even``        ``if` `(arr[i] ``%` `2` `=``=` `0``):` `            ``# Increase count of even``            ``E ``+``=` `1` `    ``# If S is at least K``    ``if` `(S >``=` `K):``        ``return` `0` `    ``# If S + E is less than K``    ``elif` `(S ``+` `E < K):``        ``return` `-``1` `    ``# Otherwise, moves = K - S``    ``else``:``        ``return` `K ``-` `S` `# Driver Code``if` `__name__ ``=``=` `"__main__"``:` `    ``arr ``=` `[``0``, ``1``, ``1``, ``0``, ``1``]``    ``N ``=` `len``(arr)``    ``K ``=` `4``    ``print``(minStepK(arr, N, K))` `    ``# This code is contributed by ukasp.`

## C#

 `// C# program for the above approach``using` `System;``class` `GFG``{``  ` `// Function to find minimum number``// of Bitwise XOR of array elements``// with 1 required to make sum of``// the array at least K``static` `int` `minStepK(``int``[] arr, ``int` `N, ``int` `K)``{``    ` `    ``// Stores the count of``    ``// even array elements``    ``int` `E = 0;` `    ``// Stores sum of the array``    ``int` `S = 0;` `    ``// Traverse the array arr[]``    ``for``(``int` `i = 0; i < N; i++)``    ``{``        ` `        ``// Increment sum``        ``S += arr[i];` `        ``// If array element is even``        ``if` `(arr[i] % 2 == 0)` `            ``// Increase count of even``            ``E += 1;``    ``}` `    ``// If S is at least K``    ``if` `(S >= K)``        ``return` `0;` `    ``// If S + E is less than K``    ``else` `if` `(S + E < K)``        ``return` `-1;` `    ``// Otherwise, moves = K - S``    ``else``        ``return` `K - S;``}` `    ``// Driver Code``    ``public` `static` `void` `Main()``    ``{``    ``int``[] arr= { 0, 1, 1, 0, 1 };``    ``int` `N = arr.Length;``    ``int` `K = 4;``    ` `    ``Console.WriteLine(minStepK(arr, N, K));` `    ``}``}` `// This code is contributed by sanjoy_62.`

## Javascript

 ``
Output:
`1`

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

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