Add ajacency-list representation

Author: jcazevedo

src/main/java/com/packt/datastructuresandalg/lesson6/graph/AdjacencyListGraph.java

@@ -0,0 +1,27 @@
+package com.packt.datastructuresandalg.lesson6.graph;
+
+import java.util.ArrayList;
+
+public class AdjacencyListGraph {
+    ArrayList<Integer>[] adj;
+
+    public AdjacencyListGraph(int nodes) {
+        this.adj = new ArrayList[nodes];
+    }
+
+    public void addEdge(int u, int v) {
+        adj[u].add(v);
+    }
+
+    public static void main(String [] args) {
+        AdjacencyListGraph g = new AdjacencyListGraph(5);
+        g.addEdge(0, 1);
+        g.addEdge(0, 3);
+        g.addEdge(1, 4);
+        g.addEdge(2, 4);
+        g.addEdge(2, 5);
+        g.addEdge(3, 1);
+        g.addEdge(4, 3);
+        g.addEdge(5, 5);
+    }
+}