Simple graph implementation

graph.go

package main

import "fmt"

type Graph struct {
	vertices map[int][]int
}

func (g *Graph) AddVertice(vert int) {
	if g.vertices == nil {
		g.vertices = make(map[int][]int)
	}
	if _, ok := g.vertices[vert]; !ok {
		g.vertices[vert] = []int{}
	}
}

func (g *Graph) AddEdge(node1, node2 int) {
	if _, ok := g.vertices[node1]; !ok {
		return
	}
	if _, ok := g.vertices[node2]; !ok {
		return
	}
	g.vertices[node1] = append(g.vertices[node1], node2)
	g.vertices[node2] = append(g.vertices[node2], node1)
}

func (g *Graph) Print() {
	for vertex, neighbors := range g.vertices {
		fmt.Printf("%d -> ", vertex)
		for _, neighbor := range neighbors {
			fmt.Printf("%d ", neighbor)
		}
		fmt.Println()
	}
}

func main() {
	g := Graph{}

	g.AddVertice(0)
	g.AddVertice(1)
	g.AddVertice(2)
	g.AddVertice(3)
	g.AddVertice(4)
	g.AddVertice(5)
	g.AddVertice(6)

	g.AddEdge(3, 1)
	g.AddEdge(3, 4)
	g.AddEdge(4, 2)
	g.AddEdge(4, 5)
	g.AddEdge(1, 2)
	g.AddEdge(1, 0)
	g.AddEdge(0, 2)
	g.AddEdge(6, 5)

	g.Print()
}