From 2311b9ea9ec8780579d8c1743c28d21627b70fd9 Mon Sep 17 00:00:00 2001
From: nandani-01 <125036796+nandani-01@users.noreply.github.com>
Date: Sun, 22 Oct 2023 14:51:06 +0530
Subject: [PATCH] Create topological-sort

fixing the issue #955
---
 topological-sort | 108 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)
 create mode 100644 topological-sort

diff --git a/topological-sort b/topological-sort
new file mode 100644
index 00000000..ddea78af
--- /dev/null
+++ b/topological-sort
@@ -0,0 +1,108 @@
+// A C++ program to print topological
+// sorting of a DAG
+#include <bits/stdc++.h>
+using namespace std;
+
+// Class to represent a graph
+class Graph {
+    // No. of vertices'
+    int V;
+
+    // Pointer to an array containing adjacency listsList
+    list<int>* adj;
+
+    // A function used by topologicalSort
+    void topologicalSortUtil(int v, bool visited[],
+                             stack<int>& Stack);
+
+public:
+    // Constructor
+    Graph(int V);
+
+    // function to add an edge to graph
+    void addEdge(int v, int w);
+
+    // prints a Topological Sort of
+    // the complete graph
+    void topologicalSort();
+};
+
+Graph::Graph(int V)
+{
+    this->V = V;
+    adj = new list<int>[V];
+}
+
+void Graph::addEdge(int v, int w)
+{
+    // Add w to v’s list.
+    adj[v].push_back(w);
+}
+
+// A recursive function used by topologicalSort
+void Graph::topologicalSortUtil(int v, bool visited[],
+                                stack<int>& Stack)
+{
+    // Mark the current node as visited.
+    visited[v] = true;
+
+    // Recur for all the vertices
+    // adjacent to this vertex
+    list<int>::iterator i;
+    for (i = adj[v].begin(); i != adj[v].end(); ++i)
+        if (!visited[*i])
+            topologicalSortUtil(*i, visited, Stack);
+
+    // Push current vertex to stack
+    // which stores result
+    Stack.push(v);
+}
+
+// The function to do Topological Sort.
+// It uses recursive topologicalSortUtil()
+void Graph::topologicalSort()
+{
+    stack<int> Stack;
+
+    // Mark all the vertices as not visited
+    bool* visited = new bool[V];
+    for (int i = 0; i < V; i++)
+        visited[i] = false;
+
+    // Call the recursive helper function
+    // to store Topological
+    // Sort starting from all
+    // vertices one by one
+    for (int i = 0; i < V; i++)
+        if (visited[i] == false)
+            topologicalSortUtil(i, visited, Stack);
+
+    // Print contents of stack
+    while (Stack.empty() == false) {
+        cout << Stack.top() << " ";
+        Stack.pop();
+    }
+
+    delete[] visited;
+}
+
+// Driver Code
+int main()
+{
+    // Create a graph given in the above diagram
+    Graph g(6);
+    g.addEdge(5, 2);
+    g.addEdge(5, 0);
+    g.addEdge(4, 0);
+    g.addEdge(4, 1);
+    g.addEdge(2, 3);
+    g.addEdge(3, 1);
+
+    cout << "Following is a Topological Sort of the given "
+            "graph \n";
+
+    // Function Call
+    g.topologicalSort();
+
+    return 0;
+}