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# Sum of elements from an array having even parity

• Difficulty Level : Basic
• Last Updated : 10 Nov, 2022

Given an array arr[], the task is to calculate the sum of the elements from the given array which has even parity i.e. the number of set bits is even using bitwise operator.

Examples:

Input: arr[] = {2, 4, 3, 5, 9}
Output: 17
Only 3(0011), 5(0101) and 9(1001) have even parity
So 3 + 5 + 9 = 17

Input: arr[] = {1, 5, 4, 16, 10}
Output: 15

Approach: Initialize a variable sum = 0 and traverse the array from 0 to n – 1 while counting the number of set bits in arr[i] using Brian Kernighan’s Algorithm. If the count is even then update sum = sum + arr[i]. Print the sum in the end.

Below is the implementation of the above approach:

## C++

 `// C++ program to find the sum of the elements``// from an array which have even parity``#include ``using` `namespace` `std;` `// Function that returns true if x has even parity``bool` `checkEvenParity(``int` `x)``{``    ``// We basically count set bits``    ``// https://www.geeksforgeeks.org/count-set-bits-in-an-integer/``    ``int` `parity = 0;``    ``while` `(x != 0) {``        ``x = x & (x - 1);``        ``parity++;``    ``}` `    ``if` `(parity % 2 == 0)``        ``return` `true``;``    ``else``        ``return` `false``;``}` `// Function to return the sum of the elements``// from an array which have even parity``long` `sumlist(``int` `a[], ``int` `n)``{``    ``long` `sum = 0;` `    ``for` `(``int` `i = 0; i < n; i++) {` `        ``// If a[i] has even parity``        ``if` `(checkEvenParity(a[i]))``            ``sum += a[i];``    ``}``    ``return` `sum;``}` `// Driver code``int` `main()``{``    ``int` `arr[] = { 2, 4, 3, 5, 9 };` `    ``int` `n = ``sizeof``(arr) / ``sizeof``(arr);` `    ``cout << sumlist(arr, n);``    ``return` `0;``}`

## Java

 `// Java program to find the sum of the elements``// from an array which have even parity` `import` `java.io.*;` `class` `GFG {` `// Function that returns true if x has even parity``static` `boolean` `checkEvenParity(``int` `x)``{``    ``// We basically count set bits``    ``// https://www.geeksforgeeks.org/count-set-bits-in-an-integer/``    ``int` `parity = ``0``;``    ``while` `(x != ``0``) {``        ``x = x & (x - ``1``);``        ``parity++;``    ``}` `    ``if` `(parity % ``2` `== ``0``)``        ``return` `true``;``    ``else``        ``return` `false``;``}` `// Function to return the sum of the elements``// from an array which have even parity``static` `long` `sumlist(``int` `a[], ``int` `n)``{``    ``long` `sum = ``0``;` `    ``for` `(``int` `i = ``0``; i < n; i++) {` `        ``// If a[i] has even parity``        ``if` `(checkEvenParity(a[i]))``            ``sum += a[i];``    ``}``    ``return` `sum;``}` `// Driver code` `    ``public` `static` `void` `main (String[] args) {``            ``int` `arr[] = { ``2``, ``4``, ``3``, ``5``, ``9` `};` `    ``int` `n =arr.length;` `    ``System.out.println(sumlist(arr, n));``    ``}``}``// This code is contributed by  inder_verma..`

## Python3

 `# Python3 program to find the sum of the elements``# from an array which have even parity` `# Function that returns true if x``# has even parity``def` `checkEvenParity(x):``    ` `    ``# We basically count set bits``    ``# https://www.geeksforgeeks.org/count-set-bits-in-an-integer/``    ``parity ``=` `0``    ``while` `(x !``=` `0``):``        ``x ``=` `x & (x ``-` `1``)``        ``parity ``+``=` `1` `    ``if` `(parity ``%` `2` `=``=` `0``):``        ``return` `True``    ``else``:``        ``return` `False` `# Function to return the sum of the elements``# from an array which have even parity``def` `sumlist(a, n):``    ``sum` `=` `0``    ``for` `i ``in` `range``(n):``        ` `        ``# If a[i] has even parity``        ``if` `(checkEvenParity(a[i])):``            ``sum` `+``=` `a[i]``    ``return` `sum` `# Driver code``if` `__name__ ``=``=` `'__main__'``:``    ``arr ``=` `[ ``2``, ``4``, ``3``, ``5``, ``9` `]``    ``n ``=` `len``(arr)``    ``print``(sumlist(arr, n))` `# This code is contributed by 29AjayKumar.`

## C#

 `// C# program to find the sum of the elements``// from an array which have even parity` `using` `System ;` `class` `GFG {` `// Function that returns true if x has even parity``static` `bool` `checkEvenParity(``int` `x)``{``    ``// We basically count set bits``    ``// https://www.geeksforgeeks.org/count-set-bits-in-an-integer/``    ``int` `parity = 0;``    ``while` `(x != 0) {``        ``x = x & (x - 1);``        ``parity++;``    ``}` `    ``if` `(parity % 2 == 0)``        ``return` `true``;``    ``else``        ``return` `false``;``}` `// Function to return the sum of the elements``// from an array which have even parity``static` `long` `sumlist(``int` `[]a, ``int` `n)``{``    ``long` `sum = 0;` `    ``for` `(``int` `i = 0; i < n; i++) {` `        ``// If a[i] has even parity``        ``if` `(checkEvenParity(a[i]))``            ``sum += a[i];``    ``}``    ``return` `sum;``}` `// Driver code` `    ``public` `static` `void` `Main () {``            ``int` `[]arr = { 2, 4, 3, 5, 9 };` `    ``int` `n =arr.Length;` `    ``Console.WriteLine(sumlist(arr, n));``    ``}``    ``// This code is contributed by Ryuga``}`

## PHP

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## Javascript

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Output

`17`

Time complexity: O(nlogn)
Auxiliary space: O(1)

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