Solve problems that are commonly asked in C++ coding interviews related to common data structures.

Ace the C++ Coding Interview

Data structures are among the fundamentals of computer science and are often a core decision in developing efficient programs. They are categorized as a vital benchmark of computer science knowledge when it comes to industry interviews. This module contains a detailed review of common data structures in C++. We'll also become well-equipped with different data structures by implementing them.
By the end of this module, we'll have expertise in solving problems in data structures.

Data Structures



# Types of Graphs

There are two common types of graphs:

1. Undirected
2. Directed

## Undirected Graph

In an undirected graph, the edges are by default, **bi-directional**. For a **pair (2, 3)**, there exists an edge between vertex **2** and **3** without any specific direction. You can go from vertex **2** to **3** or ,vice versa, from **3** to **2** .

Let's calculate the maximum possible edges for an undirected graph. We are denoting an edge between vertex **a** and **b** as **(a, b)**. So, the maximum possible edges of a graph with **n** vertices will be all possible pairs of vertices of that graph, assuming that there are no self loops. 

If a graph has **n** vertices, then there are **C(n,2)** possible pairs of vertices according to Combinatorics. Solving **C(n,2)** by binomial coefficients gives us $\frac{n(n-1)}{2}$. Hence, there are $\frac{n(n-1)}{2}$ maximum possible edges in an undirected graph. 

You can see an example of an undirected graph below:

This lesson showcases the two main categories of graphs.