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# Check in binary array the number represented by a subarray is odd or even

• Difficulty Level : Easy
• Last Updated : 13 Jul, 2022

Given an array such that all its terms is either 0 or 1.You need to tell the number represented by a subarray a[l..r] is odd or even

Examples :

```Input : arr = {1, 1, 0, 1}
l = 1, r = 3
Output : odd
number represented by arr[l...r] is
101 which 5 in decimal form which is
odd

Input :  arr = {1, 1, 1, 1}
l = 0, r = 3
Output : odd```

The important point to note here is all the odd numbers in binary form have 1 as their rightmost bit and all even numbers have 0 as their rightmost bit.
The reason is simple all other bits other than the rightmost bit have even values and the sum of even numbers is always even. Now the rightmost bit can have a value of either 1 or 0 as we know even + odd = odd so when the rightmost bit is 1 the number is odd and when it is 0 the number is even.
So to solve this problem we have to just check if a[r] is 0 or 1 and accordingly print odd or even

Implementation:

## C++

 `// C++ program to find if a subarray``// is even or odd.``#include``using` `namespace` `std;` `// prints if subarray is even or odd``void` `checkEVENodd (``int` `arr[], ``int` `n, ``int` `l, ``int` `r)``{``    ``// if arr[r] = 1 print odd``    ``if` `(arr[r] == 1)``        ``cout << ``"odd"` `<< endl;` `    ``// if arr[r] = 0 print even``    ``else``        ``cout << ``"even"` `<< endl;``}` `// driver code``int` `main()``{``    ``int` `arr[] = {1, 1, 0, 1};``    ``int` `n = ``sizeof``(arr)/``sizeof``(arr);``    ``checkEVENodd (arr, n, 1, 3);``    ``return` `0;``}`

## Java

 `// java program to find if a subarray``// is even or odd.``import` `java.io.*;` `class` `GFG``{``    ``// prints if subarray is even or odd``    ``static` `void` `checkEVENodd (``int` `arr[], ``int` `n, ``int` `l, ``int` `r)``    ``{``        ``// if arr[r] = 1 print odd``        ``if` `(arr[r] == ``1``)``            ``System.out.println( ``"odd"``) ;``    ` `        ``// if arr[r] = 0 print even``        ``else``            ``System.out.println ( ``"even"``) ;``    ``}` `    ``// driver code``    ``public` `static` `void` `main (String[] args)``    ``{``        ``int` `arr[] = {``1``, ``1``, ``0``, ``1``};``        ``int` `n = arr.length;``        ``checkEVENodd (arr, n, ``1``, ``3``);``        ` `        ` `    ``}``}` `// This article is contributed by vt_m.`

## Python3

 `# Python3 program to find if a``# subarray is even or odd.` `# Prints if subarray is even or odd``def` `checkEVENodd (arr, n, l, r):` `    ``# if arr[r] = 1 print odd``    ``if` `(arr[r] ``=``=` `1``):``        ``print``(``"odd"``)` `    ``# if arr[r] = 0 print even``    ``else``:``        ``print``(``"even"``)` `# Driver code``arr ``=` `[``1``, ``1``, ``0``, ``1``]``n ``=` `len``(arr)``checkEVENodd (arr, n, ``1``, ``3``)` `# This code is contributed by Anant Agarwal.`

## C#

 `// C# program to find if a subarray``// is even or odd.``using` `System;`` ` `class` `GFG {``    ` `    ``// prints if subarray is even or odd``    ``static` `void` `checkEVENodd (``int` `[]arr,``                     ``int` `n, ``int` `l, ``int` `r)``    ``{``        ` `        ``// if arr[r] = 1 print odd``        ``if` `(arr[r] == 1)``            ``Console.WriteLine( ``"odd"``) ;``     ` `        ``// if arr[r] = 0 print even``        ``else``            ``Console.WriteLine( ``"even"``) ;``    ``}`` ` `    ``// driver code``    ``public` `static` `void` `Main()``    ``{``        ` `        ``int` `[]arr = {1, 1, 0, 1};``        ``int` `n = arr.Length;``        ` `        ``checkEVENodd (arr, n, 1, 3);``    ``}``}`` ` `// This article is contributed by Anant Agarwal.`

## PHP

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## Javascript

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Output

`odd`

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

This article is contributed by Ayush Jha. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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