c++ - I'm intrested in finding the time complexity of a map with two keys

Question

I am trying to convert the entire elements of a matrix in to a hashmap. for that what i tried is using map<pair<int,int>,int>mp;

where pair<int,int> are the array indices and the value is the value in the element of a matrix. so i tried this way mp[{i,j}]=value;

It works fine but what i am interested in is finding the time complexity .In general if there and n keys maping to a value what will be the time complexity and how.

Answer 1

Just to clarify, map container in C++ is a tree-based structure. You mentioned using a hashmap. unordered_map is a hash-based container in C++.

As for the unordered_map (https://en.cppreference.com/w/cpp/container/unordered_map):

Unordered map is an associative container that contains key-value pairs with unique keys. Search, insertion, and removal of elements have average constant-time complexity.