Final fixes on ACO (eugenp#1339)

* Ant Colony Optimization

* Updated code for Ant Colony

algorithms/pom.xml

@@ -9,6 +9,7 @@
 		<junit.version>4.12</junit.version>
 		<maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>
 		<exec-maven-plugin.version>1.5.0</exec-maven-plugin.version>
+		<lombok.version>1.16.12</lombok.version>
 	</properties>
 
 	<dependencies>
@@ -18,6 +19,12 @@
 			<version>${junit.version}</version>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>${lombok.version}</version>
+            <scope>provided</scope>
+        </dependency>
 	</dependencies>
 
 	<build>

core-java/src/main/java/com/baeldung/algorithms/RunAlgorithm.java → algorithms/src/main/java/com/baeldung/algorithms/RunAlgorithm.java

@@ -9,13 +9,14 @@
 
 public class RunAlgorithm {
 
-	public static void main(String[] args) {
+	public static void main(String[] args) throws InstantiationException, IllegalAccessException {
 		Scanner in = new Scanner(System.in);
 		System.out.println("Run algorithm:");
 		System.out.println("1 - Simulated Annealing");
 		System.out.println("2 - Slope One");
 		System.out.println("3 - Simple Genetic Algorithm");
 		System.out.println("4 - Ant Colony");
+		System.out.println("5 - Dijkstra");
 		int decision = in.nextInt();
 		switch (decision) {
 		case 1:
@@ -33,6 +34,9 @@ public static void main(String[] args) {
 			AntColonyOptimization antColony = new AntColonyOptimization(21);
 			antColony.startAntOptimization();
 			break;
+		case 5:
+			System.out.println("Please run the DijkstraAlgorithmTest.");
+			break;
 		default:
 			System.out.println("Unknown option");
 			break;

algorithms/src/main/java/com/baeldung/algorithms/ga/ant_colony/AntColonyOptimization.java

@@ -0,0 +1,203 @@
+package com.baeldung.algorithms.ga.ant_colony;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.OptionalInt;
+import java.util.Random;
+import java.util.stream.IntStream;
+
+public class AntColonyOptimization {
+
+    private double c = 1.0;
+    private double alpha = 1;
+    private double beta = 5;
+    private double evaporation = 0.5;
+    private double Q = 500;
+    private double antFactor = 0.8;
+    private double randomFactor = 0.01;
+
+    private int maxIterations = 1000;
+
+    private int numberOfCities;
+    private int numberOfAnts;
+    private double graph[][];
+    private double trails[][];
+    private List<Ant> ants = new ArrayList<>();
+    private Random random = new Random();
+    private double probabilities[];
+
+    private int currentIndex;
+
+    private int[] bestTourOrder;
+    private double bestTourLength;
+
+    public AntColonyOptimization(int noOfCities) {
+        graph = generateRandomMatrix(noOfCities);
+        numberOfCities = graph.length;
+        numberOfAnts = (int) (numberOfCities * antFactor);
+
+        trails = new double[numberOfCities][numberOfCities];
+        probabilities = new double[numberOfCities];
+        IntStream.range(0, numberOfAnts)
+            .forEach(i -> ants.add(new Ant(numberOfCities)));
+    }
+
+    /**
+     * Generate initial solution
+     */
+    public double[][] generateRandomMatrix(int n) {
+        double[][] randomMatrix = new double[n][n];
+        IntStream.range(0, n)
+            .forEach(i -> IntStream.range(0, n)
+                .forEach(j -> randomMatrix[i][j] = Math.abs(random.nextInt(100) + 1)));
+        return randomMatrix;
+    }
+
+    /**
+     * Perform ant optimization
+     */
+    public void startAntOptimization() {
+        IntStream.rangeClosed(1, 3)
+            .forEach(i -> {
+                System.out.println("Attempt #" + i);
+                solve();
+            });
+    }
+
+    /**
+     * Use this method to run the main logic
+     */
+    public int[] solve() {
+        setupAnts();
+        clearTrails();
+        IntStream.range(0, maxIterations)
+            .forEach(i -> {
+                moveAnts();
+                updateTrails();
+                updateBest();
+            });
+        System.out.println("Best tour length: " + (bestTourLength - numberOfCities));
+        System.out.println("Best tour order: " + Arrays.toString(bestTourOrder));
+        return bestTourOrder.clone();
+    }
+
+    /**
+     * Prepare ants for the simulation
+     */
+    private void setupAnts() {
+        IntStream.range(0, numberOfAnts)
+            .forEach(i -> {
+                ants.forEach(ant -> {
+                    ant.clear();
+                    ant.visitCity(-1, random.nextInt(numberOfCities));
+                });
+            });
+        currentIndex = 0;
+    }
+
+    /**
+     * At each iteration, move ants
+     */
+    private void moveAnts() {
+        IntStream.range(currentIndex, numberOfCities - 1)
+            .forEach(i -> {
+                ants.forEach(ant -> ant.visitCity(currentIndex, selectNextCity(ant)));
+                currentIndex++;
+            });
+    }
+
+    /**
+     * Select next city for each ant
+     */
+    private int selectNextCity(Ant ant) {
+        int t = random.nextInt(numberOfCities - currentIndex);
+        if (random.nextDouble() < randomFactor) {
+            OptionalInt cityIndex = IntStream.range(0, numberOfCities)
+                .filter(i -> i == t && !ant.visited(i))
+                .findFirst();
+            if (cityIndex.isPresent()) {
+                return cityIndex.getAsInt();
+            }
+        }
+        calculateProbabilities(ant);
+        double r = random.nextDouble();
+        double total = 0;
+        for (int i = 0; i < numberOfCities; i++) {
+            total += probabilities[i];
+            if (total >= r) {
+                return i;
+            }
+        }
+
+        throw new RuntimeException("There are no other cities");
+    }
+
+    /**
+     * Calculate the next city picks probabilites
+     */
+    public void calculateProbabilities(Ant ant) {
+        int i = ant.trail[currentIndex];
+        double pheromone = 0.0;
+        for (int l = 0; l < numberOfCities; l++) {
+            if (!ant.visited(l)) {
+                pheromone += Math.pow(trails[i][l], alpha) * Math.pow(1.0 / graph[i][l], beta);
+            }
+        }
+        for (int j = 0; j < numberOfCities; j++) {
+            if (ant.visited(j)) {
+                probabilities[j] = 0.0;
+            } else {
+                double numerator = Math.pow(trails[i][j], alpha) * Math.pow(1.0 / graph[i][j], beta);
+                probabilities[j] = numerator / pheromone;
+            }
+        }
+    }
+
+    /**
+     * Update trails that ants used
+     */
+    private void updateTrails() {
+        for (int i = 0; i < numberOfCities; i++) {
+            for (int j = 0; j < numberOfCities; j++) {
+                trails[i][j] *= evaporation;
+            }
+        }
+        for (Ant a : ants) {
+            double contribution = Q / a.trailLength(graph);
+            for (int i = 0; i < numberOfCities - 1; i++) {
+                trails[a.trail[i]][a.trail[i + 1]] += contribution;
+            }
+            trails[a.trail[numberOfCities - 1]][a.trail[0]] += contribution;
+        }
+    }
+
+    /**
+     * Update the best solution
+     */
+    private void updateBest() {
+        if (bestTourOrder == null) {
+            bestTourOrder = ants.get(0).trail;
+            bestTourLength = ants.get(0)
+                .trailLength(graph);
+        }
+        for (Ant a : ants) {
+            if (a.trailLength(graph) < bestTourLength) {
+                bestTourLength = a.trailLength(graph);
+                bestTourOrder = a.trail.clone();
+            }
+        }
+    }
+
+    /**
+     * Clear trails after simulation
+     */
+    private void clearTrails() {
+        IntStream.range(0, numberOfCities)
+            .forEach(i -> {
+                IntStream.range(0, numberOfCities)
+                    .forEach(j -> trails[i][j] = c);
+            });
+    }
+
+}

algorithms/src/main/java/com/baeldung/algorithms/dijkstra/Dijkstra.java → algorithms/src/main/java/com/baeldung/algorithms/ga/dijkstra/Dijkstra.java

@@ -1,4 +1,4 @@
-package com.baeldung.algorithms.dijkstra;
+package com.baeldung.algorithms.ga.dijkstra;
 
 import java.util.HashSet;
 import java.util.LinkedList;

algorithms/src/main/java/com/baeldung/algorithms/dijkstra/Graph.java → algorithms/src/main/java/com/baeldung/algorithms/ga/dijkstra/Graph.java

@@ -1,4 +1,4 @@
-package com.baeldung.algorithms.dijkstra;
+package com.baeldung.algorithms.ga.dijkstra;
 
 import java.util.HashSet;
 import java.util.Set;

algorithms/src/main/java/com/baeldung/algorithms/dijkstra/Node.java → algorithms/src/main/java/com/baeldung/algorithms/ga/dijkstra/Node.java

@@ -1,4 +1,4 @@
-package com.baeldung.algorithms.dijkstra;
+package com.baeldung.algorithms.ga.dijkstra;
 
 import java.util.HashMap;
 import java.util.LinkedList;

core-java/src/test/java/com/baeldung/algorithms/AntColonyOptimizationTest.java → algorithms/src/test/java/algorithms/AntColonyOptimizationTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.algorithms;
+package algorithms;
 
 import org.junit.Assert;
 import org.junit.Test;

core-java/src/test/java/com/baeldung/algorithms/BinaryGeneticAlgorithmUnitTest.java → algorithms/src/test/java/algorithms/BinaryGeneticAlgorithmUnitTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.algorithms;
+package algorithms;
 
 import org.junit.Assert;
 import org.junit.Test;

algorithms/src/test/java/algorithms/DijkstraAlgorithmTest.java

@@ -1,10 +1,11 @@
 package algorithms;
 
-import com.baeldung.algorithms.dijkstra.Dijkstra;
-import com.baeldung.algorithms.dijkstra.Graph;
-import com.baeldung.algorithms.dijkstra.Node;
 import org.junit.Test;
 
+import com.baeldung.algorithms.ga.dijkstra.Dijkstra;
+import com.baeldung.algorithms.ga.dijkstra.Graph;
+import com.baeldung.algorithms.ga.dijkstra.Node;
+
 import java.util.Arrays;
 import java.util.List;
 

core-java/src/test/java/com/baeldung/algorithms/SimulatedAnnealingTest.java → algorithms/src/test/java/algorithms/SimulatedAnnealingTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.algorithms;
+package algorithms;
 
 import org.junit.Assert;
 import org.junit.Test;