Added DFS (Recursive) - Graph (TheAlgorithms#228)

ruppysuppy · web-flow · commit b5899d5294a6 · 2020-07-14T17:34:42.000+05:30
diff --git a/Graphs/DepthFirstSearchRecursive.js b/Graphs/DepthFirstSearchRecursive.js
@@ -0,0 +1,46 @@
+class GraphUnweightedUndirected {
+  // Unweighted Undirected Graph class
+  constructor () {
+    this.connections = {}
+  }
+
+  addNode (node) {
+    // Function to add a node to the graph (connection represented by set)
+    this.connections[node] = new Set()
+  }
+
+  addEdge (node1, node2) {
+    // Function to add an edge (adds the node too if they are not present in the graph)
+    if (!(node1 in this.connections)) { this.addNode(node1) }
+    if (!(node2 in this.connections)) { this.addNode(node2) }
+    this.connections[node1].add(node2)
+    this.connections[node2].add(node1)
+  }
+
+  DFSRecursive (node, value, visited = new Set()) {
+    // DFS Function to search if a node with the given value is present in the graph
+    // checking if the searching node has been found
+    if (node === value) { return true }
+    // adding the current node to the visited set
+    visited.add(node)
+    // calling the helper function recursivly for all unvisited nodes
+    for (const neighbour of this.connections[node]) {
+      if (!visited.has(neighbour)) {
+        if (this.DFSRecursive(neighbour, value, visited)) { return true }
+      }
+    }
+    return false
+  }
+}
+
+function main () {
+  const graph = new GraphUnweightedUndirected()
+  graph.addEdge(1, 2)
+  graph.addEdge(2, 3)
+  graph.addEdge(2, 4)
+  graph.addEdge(3, 5)
+  console.log(graph.DFSRecursive(5, 1))
+  console.log(graph.DFSRecursive(5, 100))
+}
+
+main()
