A Map, also know as a Dictionary, is a collection of key-value pairs. Entries (known as associations) can be added by providing a value and a key that can be used to retrieve that value. Keys in a map are unique, though multiple keys could store the same value.
Map is also an example of an un-ordered collection. You can put keys in, but if you iterate through there is no guarantee as to the order of the values that come out.
Storing key:value pairs is a common need in programming, you've done it yourself many times in Ruby. While the Map data structure is abstract, and thereby does not specify an underlying implementation, most Maps allow you to access elements by key in constant time, aka O(1). This is a valuable feature of Maps: they are both fast, and a convenient data store. Your Map does not need to be constant time in this challenge.
Some form of Map is available in nearly every language.
While Maps are fast to access, they don't allow for ordered collections. To get a fast and ordered collection we'll look at Trees next.
Find out what the Map data structure is called in Ruby, Javascript and Java. It's vital that you're able to connect the abstract data structure with its language-specific implementation. Commit your answer in a file called notes.md.
Write and test a Map class. Do not use Ruby's Hash class. Instead, you can rely on any of the Data Structures you have implemented thus far.
Your class should conform to the following interface.
Map::new: Instantiate a new MapMap#set(key, value): Add a key-value pair. If the key is already present, replace the value. Return the valueMap#get(key): Retrieve the value stored atkeyMap#has_key?(key): Answer where or not the map has an entry forkeyMap#remove(key): Remove the entry stored atkeyMap#iterate{ |value, key| block }: Iterate through the Map, passing the block each value and key
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