```
// This file contains the simple structural implementation of
// directed & undirected graphs used within the graph package
// Author(s): [Shivam](https://github.com/Shivam010), [Tahmeed](https://github.com/Tahmeed156)
package graph
// Graph provides a structure to store the graph.
// It is safe to use its empty object.
type Graph struct {
vertices int
edges map[int]map[int]int // Stores weight of an edge
Directed bool // Differentiate directed/undirected graphs
}
// Constructor functions for graphs (undirected by default)
func New(v int) *Graph {
return &Graph{
vertices: v,
}
}
// AddVertex will add a new vertex in the graph.
// If the vertex already exists it will do nothing.
func (g *Graph) AddVertex(v int) {
if g.edges == nil {
g.edges = make(map[int]map[int]int)
}
// Check if vertex is present or not
if _, ok := g.edges[v]; !ok {
g.edges[v] = make(map[int]int)
}
}
// AddEdge will add a new edge between the provided vertices in the graph
func (g *Graph) AddEdge(one, two int) {
// Add an edge with 0 weight
g.AddWeightedEdge(one, two, 0)
}
// AddWeightedEdge will add a new weighted edge between the provided vertices in the graph
func (g *Graph) AddWeightedEdge(one, two, weight int) {
// Add vertices: one and two to the graph if they are not present
g.AddVertex(one)
g.AddVertex(two)
// And finally add the edges
// one->two and two->one for undirected graph
// one->two for directed graphs
g.edges[one][two] = weight
if !g.Directed {
g.edges[two][one] = weight
}
}
```