Index Of an Extra Element
Easy Accuracy: 50.04% Submissions: 59969 Points: 2

Given two sorted arrays of distinct elements. There is only 1 difference between the arrays. First array has one element extra added in between. Find the index of the extra element.

Example 1:

Input:
N = 7
A[] = {2,4,6,8,9,10,12}
B[] = {2,4,6,8,10,12}
Output: 4
Explanation: In the second array, 9 is
missing and it's index in the first array
is 4.

Example 2:

Input:
N = 6
A[] = {3,5,7,9,11,13}
B[] = {3,5,7,11,13}
Output: 3

You don't have to take any input. Just complete the provided function findExtra() that takes array A[], B[] and size of A[] and return the valid index (0 based indexing).

Expected Time Complexity: O(log N).
Expected Auxiliary Space: O(1).

Constraints:
2<=N<=104
1<=Ai<=105

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