# Graphs
## Components
* vertex: each node of the graph
* edges: describe realationships between vertices
## Types
* Weigthed / Not Weigthed
* Directed / Undirected
## Representation
### 1. Adjacency Matrix
An adjacency matrix, once it has been formed can give us another piece of infromatio looking at rows and columns. *Adjacency Lists* which hive us the neighbours of a given node. For example if we want to know the node 4 neighbours we just look at row or column 4.
* * *
* For an undirected graph the SPACE USAGE is
* ```n^2``` | For *n vertices*
### 2. Linked Lists storage
## Properties
* For an undirected graph the SPACE USAGE is
* ```n + e*2*2``` | For *n vertices* and *e vertices*
### Maximum total number of edges with *n* vertices
#### Undirected graph
* ```(n*(n-1))/2```
#### Directed graph
* ```(n*(n-1))```