Simple graph data structure without distance value of each nodes.

graph-data-structure.go

package main

import (
	"fmt"
)

type Graph struct {
	Vertice []*Vertex
}

type Vertex struct {
	Key      int
	Adjacent []*Vertex
}

func (g *Graph) AddVertex(vertex int) error {
	// Check is vertex available
	if isExist(vertex, g.Vertice) {
		return fmt.Errorf("vertex is exist")
	}

	// Insert vertex into graph
	g.Vertice = append(g.Vertice, &Vertex{
		Key: vertex,
	})

	return nil
}

func (g *Graph) GetVertex(vertex int) *Vertex {
	for i, v := range g.Vertice {
		if v.Key == vertex {
			return g.Vertice[i]
		}
	}

	return nil
}

func (g *Graph) AddEdge(from int, dest int) error {
	// Check is vertext exists
	fromVertex := g.GetVertex(from)
	destVertex := g.GetVertex(dest)
	if fromVertex == nil || destVertex == nil {
		return fmt.Errorf("vertex from (%v) --> (%v) is not valid", from, dest)
	}

	// Check is adjacent vertex exists or not
	if isExist(destVertex.Key, fromVertex.Adjacent) {
		return fmt.Errorf("edge from vertex (%v) --> (%v) already exists", fromVertex.Key, destVertex.Key)
	}

	// insert new adjacent for from and dest vertex
	fromVertex.Adjacent = append(fromVertex.Adjacent, destVertex)
	return nil
}

func (g *Graph) Print() {
	for _, val := range g.Vertice {
		fmt.Printf("(%v): ", val.Key)
		for i, adj := range val.Adjacent {
			if i > 0 {
				fmt.Printf(" -> ")
			}
			fmt.Printf("(%v)", adj.Key)
		}
		fmt.Println()
	}
}

func isExist(key int, vertices []*Vertex) bool {
	for _, v := range vertices {
		if v.Key == key {
			return true
		}
	}

	return false
}

func main() {
	graph := &Graph{}
	graph.AddVertex(0)
	graph.AddVertex(1)
	graph.AddVertex(2)
	graph.AddVertex(3)
	graph.AddVertex(4)
	graph.AddVertex(5)

	graph.AddEdge(0, 1)
	graph.AddEdge(0, 2)
	graph.AddEdge(0, 5)

	graph.AddEdge(1, 0)
	graph.AddEdge(2, 0)
	graph.AddEdge(5, 0)

	graph.AddEdge(2, 1)
	graph.AddEdge(2, 3)
	graph.AddEdge(2, 6)

	graph.AddEdge(1, 2)
	graph.AddEdge(3, 2)
	graph.AddEdge(6, 2)

	graph.AddEdge(6, 5)
	graph.AddEdge(5, 6)

	graph.Print()
}