First question :
Validate order list : P1, P2, D2,D1

Pick are ascending order and delivery can be any order
Solved it completely and correctly

Second Question :
Given number of order return all teh possible valid orders
n =2 orders = [ P1,P2, D1 , D2] , [P1,P2, D2,D1] , [P1 , D1, P2, D2]

Couldn't solve the second one.

Result : Rejected