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

Given a 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
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

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 rightmost bit have even values and sum of even numbers is always even .Now the rightmost bit can have value either 1 or 0 as we know even + odd = odd so when right most 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

```// C++ program to find if a subarray
// is even or odd.
#include<bits/stdc++.h>
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[0]);
checkEVENodd (arr, n, 1, 3);
return 0;
}
```

Output:

```odd
```

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

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

# GATE CS Corner    Company Wise Coding Practice

Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.
1.5 Average Difficulty : 1.5/5.0
Based on 18 vote(s)

Writing code in comment? Please use ide.geeksforgeeks.org, generate link and share the link here.