Hashtables

Java: Hashmap (Hashtable class is deprecated). C#: Dictionary (Hashtable class is deprecated too). /!\ A hash table does not guarantee that the order will remain constant over time. Hashmap in Java final Map<String, String> myLookupTable…

Arrays

A way of organizing data that enables efficient storage, retrieval, and use. An array is just a sequence of elements stored linearly. See Contiguous allocation. Languages such as C# and Java have fixed-length arrays, not Python though. Arrays…

Abstract datatype

The best simple definition I found is from Cracking the Coding Interview by Gayle Laakmann McDowell: "An abstract data type is defined by its behavior (its operations). The underlying implementation can vary. You could implement a priority…

Types of data structures

A data structure is a way of organizing data that enables efficient storage, retrieval, and use. Linear vs Non-Linear Linear Data Structures A data structure is said to be linear if its elements are arranged in a linear sequence like in an…

Linked lists

Some of the screenshots here come from the author of this best seller book. Java: LinkedList (which is a Doubly-linked list implementation) C#: LinkedList (which is a doubly-linked list too) Thinking of a linked list as a list can be a bit…