Add an adjacency-list representation for a weighted graph

Author: jcazevedo

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

@@ -0,0 +1,55 @@
+package com.packt.datastructuresandalg.lesson6.graph;
+
+import java.util.ArrayList;
+
+public class AdjacencyListWeightedGraph {
+    private class Edge {
+        int u, v, weight;
+
+        public Edge(int u, int v, int weight) {
+            this.u = u;
+            this.v = v;
+            this.weight = weight;
+        }
+    }
+
+    ArrayList<Edge>[] adj;
+
+    public AdjacencyListWeightedGraph(int nodes) {
+        this.adj = new ArrayList[nodes];
+        for (int i = 0; i < nodes; i++)
+            this.adj[i] = new ArrayList<>();
+    }
+
+    public void addEdge(int u, int v, int weight) {
+        this.adj[u].add(new Edge(u, v, weight));
+    }
+
+    @Override
+    public String toString() {
+        String res = "";
+        for (int i = 0; i < adj.length; i++) {
+            res += (i + ":");
+            for (int j = 0; j < adj[i].size(); j++) {
+                Edge edge = adj[i].get(j);
+                res += (" " + edge.v + "(" + edge.weight + ")");
+            }
+            if (i + 1 < adj.length)
+                res += "\n";
+        }
+        return res;
+    }
+
+    public static void main(String [] args) {
+        AdjacencyListWeightedGraph g = new AdjacencyListWeightedGraph(6);
+        g.addEdge(0, 1, 1);
+        g.addEdge(0, 3, 4);
+        g.addEdge(1, 4, 3);
+        g.addEdge(2, 4, 10);
+        g.addEdge(2, 5, 4);
+        g.addEdge(3, 1, 5);
+        g.addEdge(4, 3, 1);
+        g.addEdge(5, 5, 2);
+        System.out.println(g);
+    }
+}