Add Floyd-Warshall implementation

Author: jcazevedo

src/main/java/com/packt/datastructuresandalg/lesson6/floydwarshall/FloydWarshall.java

@@ -0,0 +1,64 @@
+package com.packt.datastructuresandalg.lesson6.floydwarshall;
+
+public class FloydWarshall {
+    int[][] adj;
+
+    public FloydWarshall(int nodes) {
+        this.adj = new int[nodes][nodes];
+        for (int i = 0; i < adj.length; i++) {
+            for (int j = 0; j < adj[i].length; j++) {
+                if (i == j)
+                    this.adj[i][j] = 0;
+                else
+                    this.adj[i][j] = Integer.MAX_VALUE;
+            }
+        }
+    }
+
+    public void addEdge(int u, int v, int weight) {
+        adj[u][v] = Math.min(adj[u][v], weight);
+    }
+
+    @Override
+    public String toString() {
+        String res = "";
+        for (int i = 0; i < this.adj.length; i++) {
+            res += (i + ":");
+            for (int j = 0; j < this.adj[i].length; j++)
+                res += (" " + adj[i][j]);
+            if (i + 1 < adj.length)
+                res += "\n";
+        }
+        return res;
+    }
+
+    public void run() {
+        for (int k = 0; k < adj.length; k++) {
+            for (int i = 0; i < adj.length; i++) {
+                if (adj[i][k] >= Integer.MAX_VALUE)
+                    continue;
+                for (int j = 0; j < adj.length; j++) {
+                    if (adj[k][j] >= Integer.MAX_VALUE)
+                        continue;
+                    adj[i][j] = Math.min(adj[i][j], adj[i][k] + adj[k][j]);
+                }
+            }
+        }
+    }
+
+    public static void main(String [] args) {
+        FloydWarshall g = new FloydWarshall(5);
+        g.addEdge(0, 1, 10);
+        g.addEdge(0, 3, 5);
+        g.addEdge(1, 3, 2);
+        g.addEdge(1, 2, 1);
+        g.addEdge(2, 4, 4);
+        g.addEdge(3, 1, 3);
+        g.addEdge(3, 2, 9);
+        g.addEdge(3, 4, 2);
+        g.addEdge(4, 2, 6);
+        g.run();
+        System.out.println(g);
+    }
+
+}