What is the internal implementation of unordered_map in C++11?

Can you explain how unordered_map is implemented in C++11?

Sure! In C++11, unordered_map is implemented using a hash table. It uses a hash function to compute an index for storing elements.

What are the advantages of using unordered_map over map?

The main advantage is that unordered_map provides average constant time complexity for insertions and lookups, while map has logarithmic time complexity.

How does it handle collisions?

It handles collisions using separate chaining or open addressing. In separate chaining, each bucket contains a linked list of entries.

Can you give an example of how to use unordered_map?

Certainly! Here's a simple example:

#include <unordered_map>
#include <iostream>

int main() {
    std::unordered_map<std::string, int> umap;
    umap["apple"] = 1;
    umap["banana"] = 2;
    std::cout << umap["apple"]; // Outputs 1
}

This code creates an unordered_map and adds two key-value pairs.