count number of trees in a given forest

Author: manju07

Data-Structure/Graph/countTrees.js

@@ -0,0 +1,43 @@
+'use strict';
+class Graph {
+    constructor(vertex) {
+        this.listArray = new Array(vertex + 1);
+        this.visitedArr = new Array(vertex + 1);
+        for (let index = 0; index <= vertex; index++) {
+            this.listArray[index] = [];
+            this.visitedArr[index] = 0;
+        }
+    }
+    addEdge(v, u) {
+        this.listArray[v].push(u);
+    }
+
+    dfs(startVertex) {
+        this.visitedArr[startVertex] = 1;
+        let tList = this.listArray[startVertex];
+        for (let index = 0; index < tList.length; index++) {
+            if (!this.visitedArr[tList[index]]) this.dfs(tList[index]);
+        }
+    }
+
+    countTrees() {
+        let cTrees = 0;
+        for (let index = 1; index < this.visitedArr.length; index++) {
+            if (!this.visitedArr[index]) {
+                this.dfs(index);
+                cTrees++;
+            }
+        }
+        return cTrees;
+    }
+}
+
+let g1 = new Graph(8);
+g1.addEdge(1, 2);
+g1.addEdge(1, 3);
+
+g1.addEdge(4, 5);
+g1.addEdge(4, 6);
+
+g1.addEdge(7, 8);
+console.log('Total Number of trees', g1.countTrees());