[DAY20]Hash Tables: Ice Cream Parlor

Hash Tables: Ice Cream Parlor | HackerRank

Solution1: Sorted and Binary Search.

Solution 2: Create a hash table to record the position of each cost. And traverse through the hash table. Find if the value of money minus cost exits in the keys of the has table. Also we need to further check if the cost equals money minus cost. An exception might happens when the value of money minus cost equals cost, and only one of the ice cream cost that.