Graphs/Topological_Sort at master · KnowledgeCenterYoutube/Graphs · GitHub

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Topological Sort of Directed Acyclic Graph
Detailed video explanation: https://youtu.be/3HHlOG05qEo
============================================

C++:
----
#include <iostream>
#include <queue>
#include <stack>

using namespace std;

class Graph{
    int m_v;
    vector<vector<int>> m_adj;
    void TS_rec(int s, vector<bool>& visited, stack<int>& S){
        visited[s] = true;

        for(int u: m_adj[s]){
            if(!visited[u])
                TS_rec(u, visited, S);
        }

        S.push(s);
    }
public:
    Graph(int v):m_v(v), m_adj(v){}

    void addEdge(int u, int v){
        m_adj[u].push_back(v);
    }

    void Top_Sort(){
        vector<bool> visited(m_v, false);
        stack<int> S;
        for(int i = 0; i < m_v; ++i)
            if(!visited[i]) TS_rec(i, visited, S);

        while(!S.empty()){
            cout << S.top() << " ";
            S.pop();
        }
    }
};

int main(){
    Graph G(5);
    G.addEdge(0,1);
    G.addEdge(0,3);
    G.addEdge(0,4);
    G.addEdge(1,2);
    G.addEdge(4,2);
    G.addEdge(3,4);
    G.Top_Sort();

   return 0;
}


Java:
-----
import java.util.*;
import java.lang.*;
import java.io.*;

public class Graph{
	private int m_v;
	private List<Integer>[] m_adj;
	Graph(int v){
		m_v = v;
		m_adj = new LinkedList[v];
		for(int i = 0; i < v; ++i)
			m_adj[i] = new LinkedList<Integer>();
	}

	public void addEdge(int u, int v){
		m_adj[u].add(v);
	}

	private void TS_rec(int s, boolean[] visited,Stack<Integer> S){
        visited[s] = true;
        for(int u: m_adj[s]){
            if(!visited[u])
            	TS_rec(u, visited, S);
    	}
    	S.push(s);
	}

	public void Top_Sort(){
	    boolean[] visited = new boolean[m_v];
	    Stack<Integer> S = new Stack<>();
	    for(int i = 0; i < m_v; ++i)
	        if(!visited[i]) TS_rec(i, visited, S);

	    while(!S.empty())
	        System.out.println(S.pop());
	}

    public static void main(String []args){
        Graph G = new Graph(5);
		G.addEdge(0,1);
        G.addEdge(0,3);
        G.addEdge(0,4);
        G.addEdge(1,2);
        G.addEdge(4,2);
        G.addEdge(3,4);
        G.Top_Sort();
    }
}


Python3:
-------
class Graph:
    def __init__(self, v):
        self.m_v = v
        self.m_adj = [[] for i in range(v)]

    def addEdge(self, u, v):
	    self.m_adj[u].append(v)

    def TS_rec(self, s, visited):
        visited[s] = True
        for u in self.m_adj[s]:
            if not visited[u]: self.TS_rec(u, visited)
        self.S.append(s)

    def Top_Sort(self):
        visited = [False]*self.m_v
        self.S = []
        for i in range(self.m_v):
            if not visited[i]:
                self.TS_rec(i, visited)
        print(self.S)

G = Graph(5)
G.addEdge(0,1);
G.addEdge(0,3);
G.addEdge(0,4);
G.addEdge(1,2);
G.addEdge(4,2);
G.addEdge(3,4);
G.Top_Sort()