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

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:

odd

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

This article is contributed by Ayush Jha.