Map

Question 1

Name variations for a Map (3)

Answer 1

1. Map
2. Dictionary
3. Associative Array

Question 2

Map definition…

Answer 2

An abstract Data Structure which stores data in the form of key/value pairs.

Question 3

What is an element in a Map?

Answer 3

A key/value pair forms an element.

Question 4

A real-world example of a key/value pair.

Answer 4

ISBN book number. The ISBN is the key and the book is the value.

Question 5

An array is indexed using a numerical value. What value do we use to index a map?

Answer 5

The keys.

Question 6

Can a map contain duplicate keys?

Answer 6

No.

Question 7

Should you use mutable keys?

Answer 7

No.

Question 8

What Data Type can a key be?

Answer 8

Any, primitive or Object. Just make sure that for Objects they are immutable and that their object and value equality checks are taken into consideration.

Question 9

What Data Type can a value be?

Answer 9

Anything.

Question 10

How many values can a Key have?

Answer 10

Only one.

Question 11

Can there be duplicates of Values within a Map?

Answer 11

Yes.

Question 12

What is the common under-the-hood data structure implemented by a Map?

Answer 12

A Hash Table.

Question 13

How do Maps work? (Layman’s terms)

Answer 13

Maps are built on HashTables, and the values in our key/value pairs are stored in memory IN these hash tables at indexes which are determined by a hash function.

Question 14

What are the BigO Time Complexities of a Map?

Answer 14

There are the same as it’s underlying data structure.. the Hash Table.