Question:

Given two arrays arr1 and arr2 and a window size K, remove elements from prefix arr2 such that no common element exists in first K-window of arr1 and arr2.

Example - 1 :-
arr1 = [1, 2, 3, 4, 5]
arr2 = [3, 3, 3, 4, 5, 6, 1, 2]
K = 3
Output:- [4, 5, 6, 1, 2]

First K-window of arr1 = [1, 2, 3]
First K-window of arr2 = [3, 3, 3]
Here all the three elements of K-window of arr2 are present in arr1.
So remove all the three.

Now, arr2 = [4, 5, 6, 1, 2]

New K-window of arr2 = [4, 5, 6]

No common elements in both K-windows. So we stop removing elements.

Output:- [4, 5, 6, 1, 2]

Example - 2 :-
arr1 = [1, 2, 3, 4, 5]
arr2 = [1, 4, 3, 2, 4]
K = 3
Output:- [4, 4]

First K-window of arr1 = [1, 2, 3]
First K-window of arr2 = [1, 4,3]

1 and 3 are common elements here. Remove them.

Now arr2 = [4, 2, 4]

First K-window of arr1 = [1, 2, 3]
First K-window of arr2 = [4, 2, 4]

2 is the common element here, remove it.

Now arr2 = [4, 4]

Final output:- [4, 4]

Please can someone help me to solve this. Any approach would be appreciated.

This was asked in one of the Google interviews Screening Round