graphs

Author: whoparthgarg

17. Graphs/04 Topological Sorting.cpp

@@ -0,0 +1,62 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+void addEdge(vector<int> adj[], int u, int v)
+{
+	adj[u].push_back(v);
+}
+
+void topologicalSort(vector<int> adj[], int v)//time comp. O(V+E) ; space comp. O(V)
+{
+	vector<int> inDegree(v, 0);
+
+	for (int i = 0; i < v; i++)
+	{
+		for (auto x : adj[i])
+		{
+			inDegree[x]++;
+		}
+	}
+
+	queue<int> q;
+
+	for (int i = 0; i < v; i++)
+	{
+		if (inDegree[i] == 0)
+		{
+			q.push(i);
+		}
+	}
+
+	while (!q.empty())
+	{
+		int u = q.front();
+		q.pop();
+
+		cout << u << " ";
+
+		for (auto x : adj[u])
+		{
+			inDegree[x]--;
+			if (inDegree[x] == 0)
+			{
+				q.push(x);
+			}
+		}
+	}
+}
+
+int main()
+{
+	int v = 5;
+	vector<int> adj[v];
+
+	addEdge(adj, 0, 2);
+	addEdge(adj, 0, 3);
+	addEdge(adj, 1, 3);
+	addEdge(adj, 1, 4);
+	addEdge(adj, 2, 3);
+
+	topologicalSort(adj, v);
+	return 0;
+}