topological sorting of a DAG

Topplogical_sort.cpp

@@ -0,0 +1,58 @@
+    //Topological sorting 
+    //only Directed Acyclic Graph(DAG) has a valid topological ordering.
+    //Algorithm : begin with any node exploring only unvisited nodes....on recursive callback of the DFS add current node to the topological ordering in reverse order
+
+    #include <bits/stdc++.h>
+    using namespace std;
+
+    #define pb push_back 
+    #define MAX 100001
+
+    bool visited[MAX];
+    vector<int> G[MAX];
+    vector<int> topological;
+
+    void dfs(int node){
+
+    	visited[node] = true;
+
+    	for(int i=0 ; i<G[node].size() ; i++){
+
+    		int current = G[node][i];
+    		if(!visited[current])
+    			dfs(current);
+
+    	}
+
+    	topological.pb(node);
+
+    }
+
+
+    int main() {
+
+    	int edges,nodes;
+    	cin>>nodes>>edges;
+
+    	memset(visited,false,sizeof(visited));
+
+    	for(int i=0 ; i<edges ; i++){
+    		int u,v;
+    		cin>>u>>v;
+    		G[u].pb(v);
+    	}
+
+
+    	for(int i=0 ; i<nodes ; i++){
+    		if(!visited[i])
+    			dfs(i);
+    	}
+
+    	reverse(topological.begin(), topological.end());
+    	for(int i=0 ; i<topological.size() ; i++){
+    		cout<<topological[i]<<" ";
+    	}
+
+    	return 0;
+    }
+