[new concept] Jim and the Orders

This problem becomes really easy if we use a hashmap.

The Hashmap:
A data structure very much like an array, but the "index" of this array can be any data type. This "index" is called "key". The data associated with each key is called its "value".
For example:
"Key1" : 1023
"Key2" : "Hello"
12.13 : True

An advantage of hashmap is that the time required to extract a value given it's key is constant (O(1)).

In python, hashmaps are called "dictionaries".

For this problem, I created a dictionary with the keys being natural numbers, representing the position of each customer in the line (1, 2, 3, ...) and the value being the time for serving the order.

Then I sorted the dictionary by value. The keys should now be in correct order!
One way to do it in python is this:

sorted_keys = sorted(dict.items(), key = lambda kv:(kv[1], kv[0]))

This returns an array of tuples (key, value) of the dictionary sorted by value.

Just extract the keys part in a separate array, and return it.