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.