El primer recorrido en profundidad (o búsqueda) de un gráfico es similar al primer recorrido en profundidad (DFS) de un árbol . El único inconveniente aquí es que, a diferencia de los árboles, los gráficos pueden contener ciclos, por lo que un Node puede visitarse dos veces. Para evitar procesar un Node más de una vez, use una array visitada booleana.
Ejemplo:
C++
// An Iterative C++ program to do DFS traversal from
// a given source vertex. DFS(int s) traverses vertices
// reachable from s.
#include<bits/stdc++.h>
using namespace std;
// This class represents a directed graph using adjacency
// list representation
class Graph
{
int V; // No. of vertices
list<int> *adj; // adjacency lists
public:
Graph(int V); // Constructor
void addEdge(int v, int w); // to add an edge to graph
void DFS(int s); // prints all vertices in DFS manner
// from a given source.
};
Graph::Graph(int V)
{
this->V = V;
adj = new list<int>[V];
}
void Graph::addEdge(int v, int w)
{
adj[v].push_back(w); // Add w to v’s list.
}
// prints all not yet visited vertices reachable from s
void Graph::DFS(int s)
{
// Initially mark all vertices as not visited
vector<bool> visited(V, false);
// Create a stack for DFS
stack<int> stack;
// Push the current source node.
stack.push(s);
while (!stack.empty())
{
// Pop a vertex from stack and print it
int s = stack.top();
stack.pop();
// Stack may contain same vertex twice. So
// we need to print the popped item only
// if it is not visited.
if (!visited[s])
{
cout << s << " ";
visited[s] = true;
}
// Get all adjacent vertices of the popped vertex s
// If a adjacent has not been visited, then push it
// to the stack.
for (auto i = adj[s].begin(); i != adj[s].end(); ++i)
if (!visited[*i])
stack.push(*i);
}
}
// Driver program to test methods of graph class
int main()
{
Graph g(5); // Total 5 vertices in graph
g.addEdge(1, 0);
g.addEdge(0, 2);
g.addEdge(2, 1);
g.addEdge(0, 3);
g.addEdge(1, 4);
cout << "Following is Depth First Traversal\n";
g.DFS(0);
return 0;
}
Java
//An Iterative Java program to do DFS traversal from
//a given source vertex. DFS(int s) traverses vertices
//reachable from s.
import java.util.*;
public class GFG
{
// This class represents a directed graph using adjacency
// list representation
static class Graph
{
int V; //Number of Vertices
LinkedList<Integer>[] adj; // adjacency lists
//Constructor
Graph(int V)
{
this.V = V;
adj = new LinkedList[V];
for (int i = 0; i < adj.length; i++)
adj[i] = new LinkedList<Integer>();
}
//To add an edge to graph
void addEdge(int v, int w)
{
adj[v].add(w); // Add w to v’s list.
}
// prints all not yet visited vertices reachable from s
void DFS(int s)
{
// Initially mark all vertices as not visited
Vector<Boolean> visited = new Vector<Boolean>(V);
for (int i = 0; i < V; i++)
visited.add(false);
// Create a stack for DFS
Stack<Integer> stack = new Stack<>();
// Push the current source node
stack.push(s);
while(stack.empty() == false)
{
// Pop a vertex from stack and print it
s = stack.peek();
stack.pop();
// Stack may contain same vertex twice. So
// we need to print the popped item only
// if it is not visited.
if(visited.get(s) == false)
{
System.out.print(s + " ");
visited.set(s, true);
}
// Get all adjacent vertices of the popped vertex s
// If a adjacent has not been visited, then push it
// to the stack.
Iterator<Integer> itr = adj[s].iterator();
while (itr.hasNext())
{
int v = itr.next();
if(!visited.get(v))
stack.push(v);
}
}
}
}
// Driver program to test methods of graph class
public static void main(String[] args)
{
// Total 5 vertices in graph
Graph g = new Graph(5);
g.addEdge(1, 0);
g.addEdge(0, 2);
g.addEdge(2, 1);
g.addEdge(0, 3);
g.addEdge(1, 4);
System.out.println("Following is the Depth First Traversal");
g.DFS(0);
}
}
Python3
# An Iterative Python program to do DFS traversal from
# a given source vertex. DFS(int s) traverses vertices
# reachable from s.
# This class represents a directed graph using adjacency
# list representation
class Graph:
def __init__(self,V): # Constructor
self.V = V # No. of vertices
self.adj = [[] for i in range(V)] # adjacency lists
def addEdge(self,v, w): # to add an edge to graph
self.adj[v].append(w) # Add w to v’s list.
# prints all not yet visited vertices reachable from s
def DFS(self,s): # prints all vertices in DFS manner from a given source.
# Initially mark all vertices as not visited
visited = [False for i in range(self.V)]
# Create a stack for DFS
stack = []
# Push the current source node.
stack.append(s)
while (len(stack)):
# Pop a vertex from stack and print it
s = stack[-1]
stack.pop()
# Stack may contain same vertex twice. So
# we need to print the popped item only
# if it is not visited.
if (not visited[s]):
print(s,end=' ')
visited[s] = True
# Get all adjacent vertices of the popped vertex s
# If a adjacent has not been visited, then push it
# to the stack.
for node in self.adj[s]:
if (not visited[node]):
stack.append(node)
# Driver program to test methods of graph class
g = Graph(5); # Total 5 vertices in graph
g.addEdge(1, 0);
g.addEdge(0, 2);
g.addEdge(2, 1);
g.addEdge(0, 3);
g.addEdge(1, 4);
print("Following is Depth First Traversal")
g.DFS(0)
# This code is contributed by ankush_953
C#
// An Iterative C# program to do DFS traversal from
// a given source vertex. DFS(int s) traverses vertices
// reachable from s.
using System;
using System.Collections.Generic;
class GFG
{
// This class represents a directed graph using adjacency
// list representation
public class Graph
{
public int V; // Number of Vertices
public LinkedList<int>[] adj; // adjacency lists
// Constructor
public Graph(int V)
{
this.V = V;
adj = new LinkedList<int>[V];
for (int i = 0; i < adj.Length; i++)
adj[i] = new LinkedList<int>();
}
// To add an edge to graph
public void addEdge(int v, int w)
{
adj[v].AddLast(w); // Add w to v’s list.
}
// prints all not yet visited vertices reachable from s
public void DFS(int s)
{
// Initially mark all vertices as not visited
Boolean []visited = new Boolean[V];
// Create a stack for DFS
Stack<int> stack = new Stack<int>();
// Push the current source node
stack.Push(s);
while(stack.Count > 0)
{
// Pop a vertex from stack and print it
s = stack.Peek();
stack.Pop();
// Stack may contain same vertex twice. So
// we need to print the popped item only
// if it is not visited.
if(visited[s] == false)
{
Console.Write(s + " ");
visited[s] = true;
}
// Get all adjacent vertices of the popped vertex s
// If a adjacent has not been visited, then push it
// to the stack.
foreach(int v in adj[s])
{
if(!visited[v])
stack.Push(v);
}
}
}
}
// Driver code
public static void Main(String []args)
{
// Total 5 vertices in graph
Graph g = new Graph(5);
g.addEdge(1, 0);
g.addEdge(0, 2);
g.addEdge(2, 1);
g.addEdge(0, 3);
g.addEdge(1, 4);
Console.Write("Following is the Depth First Traversal\n");
g.DFS(0);
}
}
// This code is contributed by Arnasb Kundu
Javascript
<script>
// An Iterative Javascript program to
// do DFS traversal from a given source
// vertex. DFS(int s) traverses vertices
// reachable from s.
// This class represents a directed graph
// using adjacency list representation
class Graph{
constructor(V)
{
this.V = V;
this.adj = new Array(V);
for(let i = 0; i < this.adj.length; i++)
this.adj[i] = [];
}
// To add an edge to graph
addEdge(v, w)
{
// Add w to v’s list.
this.adj[v].push(w);
}
// Prints all not yet visited
// vertices reachable from s
DFS(s)
{
// Initially mark all vertices as not visited
let visited = [];
for(let i = 0; i < this.V; i++)
visited.push(false);
// Create a stack for DFS
let stack = [];
// Push the current source node
stack.push(s);
while(stack.length != 0)
{
// Pop a vertex from stack and print it
s = stack.pop();
// Stack may contain same vertex twice. So
// we need to print the popped item only
// if it is not visited.
if (visited[s] == false)
{
document.write(s + " ");
visited[s] = true;
}
// Get all adjacent vertices of the
// popped vertex s. If a adjacent has
// not been visited, then push it
// to the stack.
for(let node = 0;
node < this.adj[s].length;
node++)
{
if (!visited[this.adj[s][node]])
stack.push(this.adj[s][node])
}
}
}
}
// Driver code
// Total 5 vertices in graph
let g = new Graph(5);
g.addEdge(1, 0);
g.addEdge(0, 2);
g.addEdge(2, 1);
g.addEdge(0, 3);
g.addEdge(1, 4);
document.write("Following is the Depth " +
"First Traversal<br>");
g.DFS(0);
// This code is contributed by rag2127
</script>
C++
// An Iterative C++ program to do DFS traversal from
// a given source vertex. DFS(int s) traverses vertices
// reachable from s.
#include<bits/stdc++.h>
using namespace std;
// This class represents a directed graph using adjacency
// list representation
class Graph
{
int V; // No. of vertices
list<int> *adj; // adjacency lists
public:
Graph(int V); // Constructor
void addEdge(int v, int w); // to add an edge to graph
void DFS(); // prints all vertices in DFS manner
// prints all not yet visited vertices reachable from s
void DFSUtil(int s, vector<bool> &visited);
};
Graph::Graph(int V)
{
this->V = V;
adj = new list<int>[V];
}
void Graph::addEdge(int v, int w)
{
adj[v].push_back(w); // Add w to v’s list.
}
// prints all not yet visited vertices reachable from s
void Graph::DFSUtil(int s, vector<bool> &visited)
{
// Create a stack for DFS
stack<int> stack;
// Push the current source node.
stack.push(s);
while (!stack.empty())
{
// Pop a vertex from stack and print it
int s = stack.top();
stack.pop();
// Stack may contain same vertex twice. So
// we need to print the popped item only
// if it is not visited.
if (!visited[s])
{
cout << s << " ";
visited[s] = true;
}
// Get all adjacent vertices of the popped vertex s
// If a adjacent has not been visited, then push it
// to the stack.
for (auto i = adj[s].begin(); i != adj[s].end(); ++i)
if (!visited[*i])
stack.push(*i);
}
}
// prints all vertices in DFS manner
void Graph::DFS()
{
// Mark all the vertices as not visited
vector<bool> visited(V, false);
for (int i = 0; i < V; i++)
if (!visited[i])
DFSUtil(i, visited);
}
// Driver program to test methods of graph class
int main()
{
Graph g(5); // Total 5 vertices in graph
g.addEdge(1, 0);
g.addEdge(2, 1);
g.addEdge(3, 4);
g.addEdge(4, 0);
cout << "Following is Depth First Traversal\n";
g.DFS();
return 0;
}
Java
//An Iterative Java program to do DFS traversal from
//a given source vertex. DFS() traverses vertices
//reachable from s.
import java.util.*;
public class GFG
{
// This class represents a directed graph using adjacency
// list representation
static class Graph
{
int V; //Number of Vertices
LinkedList<Integer>[] adj; // adjacency lists
//Constructor
Graph(int V)
{
this.V = V;
adj = new LinkedList[V];
for (int i = 0; i < adj.length; i++)
adj[i] = new LinkedList<Integer>();
}
//To add an edge to graph
void addEdge(int v, int w)
{
adj[v].add(w); // Add w to v’s list.
}
// prints all not yet visited vertices reachable from s
void DFSUtil(int s, Vector<Boolean> visited)
{
// Create a stack for DFS
Stack<Integer> stack = new Stack<>();
// Push the current source node
stack.push(s);
while(stack.empty() == false)
{
// Pop a vertex from stack and print it
s = stack.peek();
stack.pop();
// Stack may contain same vertex twice. So
// we need to print the popped item only
// if it is not visited.
if(visited.get(s) == false)
{
System.out.print(s + " ");
visited.set(s, true);
}
// Get all adjacent vertices of the popped vertex s
// If a adjacent has not been visited, then push it
// to the stack.
Iterator<Integer> itr = adj[s].iterator();
while (itr.hasNext())
{
int v = itr.next();
if(!visited.get(v))
stack.push(v);
}
}
}
// prints all vertices in DFS manner
void DFS()
{
Vector<Boolean> visited = new Vector<Boolean>(V);
// Mark all the vertices as not visited
for (int i = 0; i < V; i++)
visited.add(false);
for (int i = 0; i < V; i++)
if (!visited.get(i))
DFSUtil(i, visited);
}
}
// Driver program to test methods of graph class
public static void main(String[] args)
{
Graph g = new Graph(5);
g.addEdge(1, 0);
g.addEdge(2, 1);
g.addEdge(3, 4);
g.addEdge(4, 0);
System.out.println("Following is Depth First Traversal");
g.DFS();
}
}
Python3
# An Iterative Python3 program to do DFS
# traversal from a given source vertex.
# DFS(s) traverses vertices reachable from s.
class Graph:
def __init__(self, V):
self.V = V
self.adj = [[] for i in range(V)]
def addEdge(self, v, w):
self.adj[v].append(w) # Add w to v’s list.
# prints all not yet visited vertices
# reachable from s
def DFSUtil(self, s, visited):
# Create a stack for DFS
stack = []
# Push the current source node.
stack.append(s)
while (len(stack) != 0):
# Pop a vertex from stack and print it
s = stack.pop()
# Stack may contain same vertex twice.
# So we need to print the popped item only
# if it is not visited.
if (not visited[s]):
print(s, end = " ")
visited[s] = True
# Get all adjacent vertices of the
# popped vertex s. If a adjacent has not
# been visited, then push it to the stack.
i = 0
while i < len(self.adj[s]):
if (not visited[self.adj[s][i]]):
stack.append(self.adj[s][i])
i += 1
# prints all vertices in DFS manner
def DFS(self):
# Mark all the vertices as not visited
visited = [False] * self.V
for i in range(self.V):
if (not visited[i]):
self.DFSUtil(i, visited)
# Driver Code
if __name__ == '__main__':
g = Graph(5) # Total 5 vertices in graph
g.addEdge(1, 0)
g.addEdge(2, 1)
g.addEdge(3, 4)
g.addEdge(4, 0)
print("Following is Depth First Traversal")
g.DFS()
# This code is contributed by PranchalK
C#
// An Iterative C# program to do DFS traversal from
// a given source vertex. DFS() traverses vertices
// reachable from s.
using System;
using System.Collections.Generic;
class GFG
{
// This class represents a directed graph using adjacency
// list representation
class Graph
{
public int V; // Number of Vertices
public List<int>[] adj; // adjacency lists
// Constructor
public Graph(int V)
{
this.V = V;
adj = new List<int>[V];
for (int i = 0; i < adj.Length; i++)
adj[i] = new List<int>();
}
// To add an edge to graph
public void addEdge(int v, int w)
{
adj[v].Add(w); // Add w to v’s list.
}
// prints all not yet visited vertices reachable from s
public void DFSUtil(int s, List<Boolean> visited)
{
// Create a stack for DFS
Stack<int> stack = new Stack<int>();
// Push the current source node
stack.Push(s);
while(stack.Count != 0)
{
// Pop a vertex from stack and print it
s = stack.Peek();
stack.Pop();
// Stack may contain same vertex twice. So
// we need to print the popped item only
// if it is not visited.
if(visited[s] == false)
{
Console.Write(s + " ");
visited[s] = true;
}
// Get all adjacent vertices of the popped vertex s
// If a adjacent has not been visited, then push it
// to the stack.
foreach(int itr in adj[s])
{
int v = itr;
if(!visited[v])
stack.Push(v);
}
}
}
// prints all vertices in DFS manner
public void DFS()
{
List<Boolean> visited = new List<Boolean>(V);
// Mark all the vertices as not visited
for (int i = 0; i < V; i++)
visited.Add(false);
for (int i = 0; i < V; i++)
if (!visited[i])
DFSUtil(i, visited);
}
}
// Driver code
public static void Main(String[] args)
{
Graph g = new Graph(5);
g.addEdge(1, 0);
g.addEdge(2, 1);
g.addEdge(3, 4);
g.addEdge(4, 0);
Console.WriteLine("Following is Depth First Traversal");
g.DFS();
}
}
// This code is contributed by 29AjayKumar
Javascript
<script>
//An Iterative Javascript program to do DFS traversal from
//a given source vertex. DFS() traverses vertices
//reachable from s.
// This class represents a directed graph using adjacency
// list representation
class Graph
{
//Constructor
constructor(V)
{
this.V=V;
this.adj = new Array(V);
for (let i = 0; i < this.adj.length; i++)
this.adj[i] = [];
}
//To add an edge to graph
addEdge(v,w)
{
this.adj[v].push(w); // Add w to v’s list.
}
// prints all not yet visited vertices reachable from s
DFSUtil(s,visited)
{
// Create a stack for DFS
let stack = [];
// Push the current source node
stack.push(s);
while(stack.length != 0)
{
// Pop a vertex from stack and print it
s = stack.pop();
// Stack may contain same vertex twice. So
// we need to print the popped item only
// if it is not visited.
if(visited[s] == false)
{
document.write(s + " ");
visited[s] = true;
}
// Get all adjacent vertices of the popped vertex s
// If a adjacent has not been visited, then push it
// to the stack.
for (let itr=0;itr<this.adj[s].length;itr++)
{
let v = this.adj[s][itr];
if(!visited[v])
stack.push(v);
}
}
}
// prints all vertices in DFS manner
DFS()
{
let visited = []
// Mark all the vertices as not visited
for (let i = 0; i < this.V; i++)
visited.push(false);
for (let i = 0; i < this.V; i++)
if (!visited[i])
this.DFSUtil(i, visited);
}
}
// Driver program to test methods of graph class
let g = new Graph(5);
g.addEdge(1, 0);
g.addEdge(2, 1);
g.addEdge(3, 4);
g.addEdge(4, 0);
document.write("Following is Depth First Traversal<br>");
g.DFS();
// This code is contributed by avanitrachhadiya2155
</script>
Publicación traducida automáticamente
Artículo escrito por GeeksforGeeks-1 y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA