What is "dictionary"

A dictionary in computer science is a data structure that maps keys to values such that given a key of their corresponding value can be efficiently retrieved.

It is commonly implemented as a hashmap that allow time research O(1) amortized. Alternatively, they can be applied as an ordered list, with search requiring a binary search and doing the search O(log N) amortized.

When marking a question with dictionary, make sure to mark it with the language being used as well.

In .Net

Dictionary<TKey, TValue>: Represents a collection of keys and values.