Category Archives: Data structures

Hash table

Hash table allows you to keep a list of key/value pairs, where each key associated with particular value. Such data structures implement abstract data type which is called either a dictionary, a map, or associative array. As an example from a real life, you can think of phonebook:

phonebookIn the phonebook a person name can be considered as a key, by which we can find a phone number.
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Deque

Deque or double-ended queue is almost the same as the queue. But, the main difference is that it provides possibility to add and remove elements from both sides of the queue. In other words it combines FIFO and LIFO principles.

deque

Double-ended queues are not heavily used in practice, but they can be useful in such task, as browser history. Let say, the browser history must contain last 10 visited URL’s. To do that we can add every visited URL to the front of the deque. Once, we are going to add 11th URL we remove URL from the back.
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