feat: add graph struct

Author: HaoKunT

Readme.md

@@ -8,4 +8,5 @@ it's some data struct using golang
 - [x] Stack
 - [x] Queue
 - [x] Heap
-- [ ] B/B+ tree
+- [ ] B/B+ tree
+- [x] Graph

go.mod

@@ -1,3 +1,5 @@
 module github.com/haokunt/go-data-struct
 
 go 1.14
+
+require github.com/stretchr/testify v1.9.0

go.sum

@@ -0,0 +1,19 @@
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+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
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+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

graph.go

@@ -0,0 +1,65 @@
+package datastruct
+
+import (
+	"fmt"
+)
+
+// Vertex is a node in graph
+type Vertex struct {
+	Name  string
+	Value interface{}
+}
+
+// Edge is a connection between two verties
+type Edge struct {
+	Cost float64
+	From string // the name of start vertex
+	To   string // the name of end vertex
+}
+
+// Graph is a collection of verties and edges
+type Graph struct {
+	//we need use map instead of list, because we need make sure the node name/id will not be duplicated
+	verties map[string]*Vertex
+	edges   []*Edge
+}
+
+// NewGraph creates a new graph
+func NewGraph(verties []*Vertex, edges []*Edge) (*Graph, error) {
+	g := new(Graph)
+	vx := make(map[string]*Vertex)
+	for _, v := range verties {
+		vx[v.Name] = v
+	}
+	for _, e := range edges {
+		_, okf := vx[e.From]
+		_, okt := vx[e.To]
+		if !okf || !okt {
+			return nil, fmt.Errorf("invalid edge: %v", e)
+		}
+	}
+	g.verties = vx
+	g.edges = edges
+	return g, nil
+}
+
+// AddVertext adds a vertex to the graph
+func (g *Graph) AddVertext(vertex *Vertex) error {
+	if _, ok := g.verties[vertex.Name]; ok {
+		return fmt.Errorf("duplicated vertex name: %s", vertex.Name)
+	}
+	g.verties[vertex.Name] = vertex
+	return nil
+}
+
+// AddEdge adds an edge to the graph
+func (g *Graph) AddEdge(edge *Edge) error {
+	if _, ok := g.verties[edge.From]; !ok {
+		return fmt.Errorf("invalid edge: %v", edge)
+	}
+	if _, ok := g.verties[edge.To]; !ok {
+		return fmt.Errorf("invalid edge: %v", edge)
+	}
+	g.edges = append(g.edges, edge)
+	return nil
+}

graph_test.go

@@ -0,0 +1,54 @@
+package datastruct
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNewGraph(t *testing.T) {
+	verties := []*Vertex{
+		{Name: "A", Value: 1},
+		{Name: "B", Value: 2},
+	}
+	edges := []*Edge{
+		{Cost: 1.0, From: "A", To: "B"},
+	}
+
+	graph, err := NewGraph(verties, edges)
+	assert.NoError(t, err)
+	assert.Equal(t, 2, len(graph.verties))
+	assert.Equal(t, 1, len(graph.edges))
+}
+
+func TestAddVertext(t *testing.T) {
+	graph, _ := NewGraph([]*Vertex{}, []*Edge{})
+
+	vertex := &Vertex{Name: "A", Value: 1}
+	err := graph.AddVertext(vertex)
+	assert.NoError(t, err)
+	assert.Equal(t, 1, len(graph.verties))
+
+	// Test adding duplicate vertex
+	err = graph.AddVertext(vertex)
+	assert.Error(t, err)
+}
+
+func TestAddEdge(t *testing.T) {
+	verties := []*Vertex{
+		{Name: "A", Value: 1},
+		{Name: "B", Value: 2},
+	}
+	graph, _ := NewGraph(verties, []*Edge{})
+
+	edge := &Edge{Cost: 1.0, From: "A", To: "B"}
+	err := graph.AddEdge(edge)
+	assert.NoError(t, err)
+
+	assert.Equal(t, 1, len(graph.edges))
+
+	// Test adding edge with invalid vertex
+	invalidEdge := &Edge{Cost: 1.0, From: "A", To: "C"}
+	err = graph.AddEdge(invalidEdge)
+	assert.Error(t, err)
+}