Find Index Pairs of Matching Elements in Arrays

##### Scenario Marketing analytics team needs to find common elements between two sorted arrays of user IDs. ##### Question Given two sorted integer arrays without duplicates, return the list of index pairs where the elements match, e.g., arr1=[1,4,5,6,7,9], arr2=[1,2,3,6,9] -> [[0,0],[3,3],[5,4]]. Follow-ups: Discuss possible edge cases. If the arrays can contain duplicates (arr1=[1,1,4,5,6,6,6,7,9], arr2=[1,2,3,6,6,9,9]), modify your algorithm to return all valid index pairs. ##### Hints Think two-pointer merge approach; handle duplicates with nested loops; analyze O(n+m) time.