InOutTimeOfNodes

README.md

@@ -353,7 +353,7 @@ This repository contains the solutions to problems done from various resources f
 - [x] [Is Graph Bipartite? - Leetcode](https://github.com/kalpak92/TechInterview2020/blob/master/src/Leetcode/BipartiteGraph.java)
 - [x] [Can Split everyone into two groups of any size - Leetcode](https://github.com/kalpak92/TechInterview2020/blob/master/src/Leetcode/PossibleBipartition.java)
 - [x] [Detect Cycle in an Undirected Graph - Leetcode](https://github.com/kalpak92/TechInterview2020/blob/master/src/Graph/CycleInUndirectedGraph.java)
-
+- [x] [In out time of nodes - Leetcode]()
 
 ## Dynamic Programming
 - [x] [Unique Paths : Basic - Leetcode](https://github.com/kalpak92/TechInterview2020/blob/master/src/Leetcode/UniquePaths.java)

src/Graph/InOutTimeOfNodes.java

@@ -0,0 +1,71 @@
+package Graph;
+
+import java.lang.reflect.Array;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * @author kalpak
+ *
+ * Given a graph, find the arrival and departure time of its vertices.
+ */
+
+public class InOutTimeOfNodes {
+    public static List<List<Integer>> createGraph(int numNodes) {
+        List<List<Integer>> graphAdjList = new ArrayList<>(numNodes);
+        for (int i = 0; i < numNodes; i++)
+            graphAdjList.add(new ArrayList<>());
+
+        return graphAdjList;
+    }
+
+    public static void addUndirectedEdge(List<List<Integer>> graph, int from, int to) {
+        graph.get(from).add(to);
+        graph.get(to).add(from);
+    }
+
+    public static int computeInOutTimeDFS(List<List<Integer>> graph, int startNode, boolean[] visited, int[] arrival, int[] departure, int time) {
+
+        // set the arrival time of vertex `v`
+        arrival[startNode] = ++time;
+
+        // mark vertex as discovered
+        visited[startNode] = true;
+
+        List<Integer> adjacencyList = graph.get(startNode);
+
+        for (int i: adjacencyList) {
+            if (!visited[i]) {
+                time = computeInOutTimeDFS(graph, i, visited, arrival, departure, time);
+            }
+        }
+
+        // set departure time of vertex `v`
+        departure[startNode] = ++time;
+        return time;
+    }
+
+    public static void main(String[] args) {
+        final int numNodes = 11;
+        List<List<Integer>> graph = createGraph(numNodes);
+
+        // Setup a graph with five connected components:
+        // {0,1,7}, {2,5}, {4,8}, {3,6,9}, {10}
+        addUndirectedEdge(graph, 0, 1);
+        addUndirectedEdge(graph, 1, 7);
+        addUndirectedEdge(graph, 7, 0);
+        addUndirectedEdge(graph, 2, 5);
+        addUndirectedEdge(graph, 4, 8);
+        addUndirectedEdge(graph, 3, 6);
+        addUndirectedEdge(graph, 6, 9);
+
+        int[] arrival = new int[numNodes];
+        int[] departure = new int[numNodes];
+
+        computeInOutTimeDFS(graph, 0, new boolean[numNodes], arrival, departure, 0);
+
+        System.out.println(Arrays.toString(arrival));
+        System.out.println(Arrays.toString(departure));
+    }
+}