# Golang program to find all paths in a graph

In this article we are going to learn how to use DFS Algorithm and breath-first searh method in golang to find all the paths in the a graph. In a graph, the nodes are depicted by the entities while the edges depict the relation between those entities. Finding all paths in a graph is a common task in graph theory and can be useful in a variety of applications.

## Algorithm

• Step 1 − First, we need to import the fmt package.

• Step 2 − Then create different structs and functions and define properties to them.

• Step 3 − Now, create the main() function. Inside the main() initialize the nodes and assign value to them.

• Step 4 − Further, create edges from these nodes by passing them as arguments in the graph struct.

• Step 5 − Now, call the AllPaths() function by passing the required nodes as arguments to the function and store the result obtained in a variable.

• Step 6 − Print the result on the screen by using fmt.Println() function.

## Example 1

In this Example we will write a go language program to find all the paths in a graph by using the depth-first search. The Depth-First Search (DFS) Algorithm is a classic Algorithm used to traverse and search graphs.

package main

import "fmt"

type Node struct {
name string
}

type Edge struct {
source *Node
dest   *Node
}

type Graph struct {
nodes []*Node
edges []*Edge
}

func (g *Graph) AddNode(n *Node) {
g.nodes = append(g.nodes, n)
}

func (g *Graph) AddEdge(s *Node, d *Node) {
e := &Edge{source: s, dest: d}
g.edges = append(g.edges, e)
}

func (g *Graph) DFS(s *Node, d *Node, visited map[*Node]bool, path []string, paths *[][]string) {
visited[s] = true
path = append(path, s.name)

if s == d {
*paths = append(*paths, path)
} else {
for _, e := range g.edges {
if e.source == s && !visited[e.dest] {
g.DFS(e.dest, d, visited, path, paths)
}
}
}

delete(visited, s)
path = path[:len(path)-1]
}

func (g *Graph) AllPaths(s *Node, d *Node) [][]string {
visited := make(map[*Node]bool)
paths := [][]string{}
path := []string{}

g.DFS(s, d, visited, path, &paths)

return paths
}

func main() {
a := &Node{name: "A"}
b := &Node{name: "B"}
c := &Node{name: "C"}
d := &Node{name: "D"}

g := &Graph{}
g.AddNode(a)
g.AddNode(b)
g.AddNode(c)
g.AddNode(d)
g.AddEdge(a, b)
g.AddEdge(b, c)
g.AddEdge(a, c)
g.AddEdge(c, d)

paths := g.AllPaths(a, d)
fmt.Println("The required paths in a graph are:", paths)
}


## Output

The required paths in a graph are: [[A B C D] [A C D]]


## Example 2

In this Example we will write a go language program to find all the paths in a graph by using the breadth first search method.

package main

import "fmt"

type Node struct {
name string
}

type Edge struct {
source *Node
dest   *Node
}

type Graph struct {
nodes []*Node
edges []*Edge
}

func (g *Graph) AddNode(n *Node) {
g.nodes = append(g.nodes, n)
}

func (g *Graph) AddEdge(s *Node, d *Node) {
e := &Edge{source: s, dest: d}
g.edges = append(g.edges, e)
}

func (g *Graph) BFS(s *Node, d *Node) [][]string {
visited := make(map[*Node]bool)
queue := [][]*Node{{s}}
paths := [][]string{}

for len(queue) > 0 {
path := queue[0]
queue = queue[1:]

node := path[len(path)-1]

if node == d {
var pathStr []string
for _, n := range path {
pathStr = append(pathStr, n.name)
}
paths = append(paths, pathStr)
}

for _, e := range g.edges {
if e.source == node && !visited[e.dest] {
newPath := append(path, e.dest)
queue = append(queue, newPath)
visited[e.dest] = true
}
}
}
return paths
}

func main() {
a := &Node{name: "A"}
b := &Node{name: "B"}
c := &Node{name: "C"}
d := &Node{name: "D"}

g := &Graph{}
g.AddNode(a)
g.AddNode(b)
g.AddNode(c)
g.AddNode(d)
g.AddEdge(a, b)
g.AddEdge(b, c)
g.AddEdge(a, c)
g.AddEdge(c, d)

paths := g.BFS(a, d)
fmt.Println("The required paths are:", paths)
}


## Output

The required paths are: [[A C D]]


## Conclusion

We have successfully compiled and executed a go language program to find all paths in a graph along with Examples. this is used in applications like network routing, social network analysis, and recommendation systems. We have shown two methods viz Breadth-First Search and Depth-First Search to implement this result.

Updated on: 05-Apr-2023

260 Views

##### Kickstart Your Career

Get certified by completing the course

Advertisements