check graph is connected or not

Author: manju07

Data-Structure/Graph/graphConnected.js

@@ -0,0 +1,44 @@
+'use strict';
+let arrayList1 = null,
+    arrayList2 = null;
+let visitedList1 = [], visitedList2 = [];
+function addEdge(u, v) {
+    arrayList1[u].push(v);
+    arrayList2[v].push(u);
+}
+function dfs1(vertex) {
+    visitedList1[vertex] = true;
+    for (const item of arrayList1[vertex]) {
+        if (!visitedList1[item]) dfs1(item);
+    }
+}
+
+function dfs2(vertex) {
+    visitedList2[vertex] = true;
+    for (const item of arrayList2[vertex]) {
+        if (!visitedList2[item]) dfs2(item);
+    }
+}
+
+function checkGraphConnectedOrNot(n) {
+    arrayList1 = new Array(n + 1);
+    arrayList2 = new Array(n + 1);
+    for (let index = 1; index <= n; index++) {
+        arrayList1[index] = [];
+        arrayList2[index] = [];
+        visitedList1[index] = false;
+        visitedList2[index] = false;
+    }
+    addEdge(1, 2);
+    addEdge(1, 3);
+    addEdge(2, 3);
+    addEdge(3, 4);
+    dfs1(1);
+    dfs2(1);
+    for (let index = 1; index <= n; index++) {
+        if (visitedList1[index] == false && visitedList2[index] == false) return false;
+    }
+    return true;
+}
+let n = 4;
+console.log('Graph is connected ? ', checkGraphConnectedOrNot(n));