Data-structures--Algorithms/Graph_Topolocial_Sort_UsingBFS.cpp at master · abhijeetgu/Data-structures--Algorithms · GitHub

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#include<iostream>
#include<map>
#include<list>
#include<queue>
using namespace std;

template<typename T>
class Graph{

  map<T,list<T> > adjList;
  public:
      Graph()
      {

      }

      void addEdge(T u,T v,bool bidir=true){

       adjList[u].push_back(v);
       if(bidir)
       {
           adjList[v].push_back(u);
       }

      }


      void bfsTopologicalSort(){
        queue<T> q;
        map<T,bool> visited;
        map<T,int> indegree;

        for(auto i:adjList)
        {
            //i is pair(node,list of nodes)
            T node = i.first;
            visited[node]=false;
            indegree[node]=0;

        }
        //In the indegrees of all nodes
        for(auto i:adjList)
        {
            T u=i.first;
            for(T v:adjList[u])
            {
                indegree[v]++;
            }
        }

        //Find out all the nodes with 0 indegree
        for(auto i:adjList)
        {
            T node=i.first;
            if(indegree[node]==0)
            {
                q.push(node);
            }
        }

        //Start with algorithm

        while(!q.empty())
        {
            T node = q.front();
            q.pop();
            cout<<node<<"-->";

            for(T neighbour:adjList[node])
            {
                indegree[neighbour]--;

                if(indegree[neighbour]==0)
                {
                    q.push(neighbour);
                }
            }
        }


      }


};
int main()
{
    Graph<string> g;
    g.addEdge("English","Programming Logic",false);
    g.addEdge("Maths","Programming Logic",false);
    g.addEdge("Programming Logic","HTML",false);
    g.addEdge("Programming Logic","Python",false);
    g.addEdge("Programming Logic","Java",false);
    g.addEdge("Programming Logic","JS",false);
    g.addEdge("Python","Web Dev",false);
    g.addEdge("HTML","CSS",false);
    g.addEdge("CSS","JS",false);
    g.addEdge("JS","Web Dev",false);
    g.addEdge("Java","Web Dev",false);
    g.addEdge("Python","Web Dev",false);


    g.bfsTopologicalSort();

    return 0;
}