From 1a0478145579fff65b051de91bf2fdabaedd37df Mon Sep 17 00:00:00 2001
From: harshil0802 <86008142+harshil0802@users.noreply.github.com>
Date: Tue, 18 Oct 2022 00:03:51 +0530
Subject: [PATCH] Create Topological_sort.cpp

---
 Topological_sort.cpp | 86 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100644 Topological_sort.cpp

diff --git a/Topological_sort.cpp b/Topological_sort.cpp
new file mode 100644
index 0000000..8d13f4b
--- /dev/null
+++ b/Topological_sort.cpp
@@ -0,0 +1,86 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+ // } Driver Code Ends
+class Solution
+{
+	public:
+	//Function to return list containing vertices in Topological order. 
+	vector<int> topoSort(int V, vector<int> adj[]) 
+	{
+	    vector<int> indegree(V,0);
+	    for(int i=0; i<V; i++){
+	        for(int j=0; j<adj[i].size(); j++){
+	            int node=adj[i][j];
+	            indegree[node]++;
+	        }
+	    }
+	 
+	    queue<int> qu;
+	    for(int i=0; i<V; i++){
+	        if(indegree[i]==0)
+	            qu.push(i);
+	    }
+	    vector<int> topo;
+	    while(!qu.empty()){
+	        int node=qu.front();
+	        qu.pop();
+	        topo.push_back(node);
+	        for(int j=0; j<adj[node].size(); j++){
+	            int nbr=adj[node][j];
+	            if(--indegree[nbr]==0)
+	                qu.push(nbr);
+	        }
+	    }
+	    return topo;
+	}
+};
+
+// { Driver Code Starts.
+
+/*  Function to check if elements returned by user
+*   contains the elements in topological sorted form
+*   V: number of vertices
+*   *res: array containing elements in topological sorted form
+*   adj[]: graph input
+*/
+int check(int V, vector <int> &res, vector<int> adj[]) {
+    
+    if(V!=res.size())
+    return 0;
+    
+    vector<int> map(V, -1);
+    for (int i = 0; i < V; i++) {
+        map[res[i]] = i;
+    }
+    for (int i = 0; i < V; i++) {
+        for (int v : adj[i]) {
+            if (map[i] > map[v]) return 0;
+        }
+    }
+    return 1;
+}
+
+int main() {
+    int T;
+    cin >> T;
+    while (T--) {
+        int N, E;
+        cin >> E >> N;
+        int u, v;
+
+        vector<int> adj[N];
+
+        for (int i = 0; i < E; i++) {
+            cin >> u >> v;
+            adj[u].push_back(v);
+        }
+        
+        Solution obj;
+        vector <int> res = obj.topoSort(N, adj);
+
+        cout << check(N, res, adj) << endl;
+    }
+    
+    return 0;
+}