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Add Algorithms Module (#936)

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* Update pom.xml

Add FindBugs reporting plugin

* Add algorithms module

Dijkstra implementation

* Update pom.xml

* Update pom.xml
This commit is contained in:
GuenHamza 2017-01-03 17:47:21 +00:00 committed by Grzegorz Piwowarek
parent 99e86c5f19
commit 49c7cc84ed
7 changed files with 267 additions and 14 deletions
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44
algorithms/pom.xml Normal file
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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.baeldung</groupId>
<artifactId>algorithms</artifactId>
<version>0.0.1-SNAPSHOT</version>
<properties>
<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>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<defaultGoal>install</defaultGoal>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven-compiler-plugin.version}</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<version>${exec-maven-plugin.version}</version>
</plugin>
</plugins>
</pluginManagement>
</build>
</project>

59
algorithms/src/main/java/com/baeldung/algorithms/dijkstra/Dijkstra.java Normal file
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package com.baeldung.algorithms.dijkstra;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Map.Entry;
import java.util.Set;
public class Dijkstra {
public static Graph calculateShortestPathFromSource(Graph graph, Node source) {
source.setDistance(0);
Set<Node> settledNodes = new HashSet<Node>();
Set<Node> unsettledNodes = new HashSet<Node>();
unsettledNodes.add(source);
while (unsettledNodes.size() != 0) {
Node currentNode = getLowestDistanceNode(unsettledNodes);
unsettledNodes.remove(currentNode);
for (Entry<Node, Integer> adjacencyPair : currentNode.getAdjacentNodes().entrySet())
{
Node adjacentNode = adjacencyPair.getKey();
Integer edgeWeigh = adjacencyPair.getValue();
if (!settledNodes.contains(adjacentNode)) {
CalculateMinimumDistance(adjacentNode, edgeWeigh, currentNode);
unsettledNodes.add(adjacentNode);
}
}
settledNodes.add(currentNode);
}
return graph;
}
private static void CalculateMinimumDistance(Node evaluationNode, Integer edgeWeigh, Node sourceNode) {
Integer sourceDistance = sourceNode.getDistance();
if (sourceDistance + edgeWeigh < evaluationNode.getDistance()) {
evaluationNode.setDistance(sourceDistance + edgeWeigh);
LinkedList<Node> shortestPath = new LinkedList<Node>(sourceNode.getShortestPath());
shortestPath.add(sourceNode);
evaluationNode.setShortestPath(shortestPath);
}
}
private static Node getLowestDistanceNode(Set<Node> unsettledNodes) {
Node lowestDistanceNode = null;
int lowestDistance = Integer.MAX_VALUE;
for (Node node : unsettledNodes) {
int nodeDistance = node.getDistance();
if (nodeDistance < lowestDistance) {
lowestDistance = nodeDistance;
lowestDistanceNode = node;
}
}
return lowestDistanceNode;
}
}

21
algorithms/src/main/java/com/baeldung/algorithms/dijkstra/Graph.java Normal file
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package com.baeldung.algorithms.dijkstra;
import java.util.HashSet;
import java.util.Set;
public class Graph {
private Set<Node> nodes = new HashSet<Node>();
public void addNode(Node nodeA) {
nodes.add(nodeA);
}
public Set<Node> getNodes() {
return nodes;
}
public void setNodes(Set<Node> nodes) {
this.nodes = nodes;
}
}

9
algorithms/src/main/java/com/baeldung/algorithms/dijkstra/Main.java Normal file
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package com.baeldung.algorithms.dijkstra;
public class Main {
public static void main(String[] args) {
}
}

58
algorithms/src/main/java/com/baeldung/algorithms/dijkstra/Node.java Normal file
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package com.baeldung.algorithms.dijkstra;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
public class Node {
private String name;
private LinkedList<Node> shortestPath = new LinkedList<Node>();
private Integer distance = Integer.MAX_VALUE;
Map<Node, Integer> adjacentNodes = new HashMap<Node, Integer>();
public Node(String name) {
this.name = name;
}
public void addDestination(Node destination, int distance) {
adjacentNodes.put(destination, distance);
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Map<Node, Integer> getAdjacentNodes() {
return adjacentNodes;
}
public void setAdjacentNodes(Map<Node, Integer> adjacentNodes) {
this.adjacentNodes = adjacentNodes;
}
public Integer getDistance() {
return distance;
}
public void setDistance(Integer distance) {
this.distance = distance;
}
public List<Node> getShortestPath() {
return shortestPath;
}
public void setShortestPath(LinkedList<Node> shortestPath) {
this.shortestPath = shortestPath;
}
}

76
algorithms/src/test/java/algorithms/DijkstraAlgorithmTest.java Normal file
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package algorithms;
import static org.junit.Assert.*;
import java.util.Arrays;
import java.util.List;
import org.junit.Test;
import com.baeldung.algorithms.dijkstra.Dijkstra;
import com.baeldung.algorithms.dijkstra.Graph;
import com.baeldung.algorithms.dijkstra.Node;
public class DijkstraAlgorithmTest {
@Test
public void whenSPPSolved_thenCorrect() {
Node nodeA = new Node("A");
Node nodeB = new Node("B");
Node nodeC = new Node("C");
Node nodeD = new Node("D");
Node nodeE = new Node("E");
Node nodeF = new Node("F");
nodeA.addDestination(nodeB, 10);
nodeA.addDestination(nodeC, 15);
nodeB.addDestination(nodeD, 12);
nodeB.addDestination(nodeF, 15);
nodeC.addDestination(nodeE, 10);
nodeD.addDestination(nodeE, 2);
nodeD.addDestination(nodeF, 1);
nodeF.addDestination(nodeE, 5);
Graph graph = new Graph();
graph.addNode(nodeA);
graph.addNode(nodeB);
graph.addNode(nodeC);
graph.addNode(nodeD);
graph.addNode(nodeE);
graph.addNode(nodeF);
graph = Dijkstra.calculateShortestPathFromSource(graph, nodeA);
List<Node> shortestPathForNodeB = Arrays.asList(nodeA);
List<Node> shortestPathForNodeC = Arrays.asList(nodeA);
List<Node> shortestPathForNodeD = Arrays.asList(nodeA, nodeB);
List<Node> shortestPathForNodeE = Arrays.asList(nodeA, nodeB, nodeD);
List<Node> shortestPathForNodeF = Arrays.asList(nodeA, nodeB, nodeD);
for(Node node : graph.getNodes()) {
switch (node.getName()) {
case "B":
assertTrue(node.getShortestPath().equals(shortestPathForNodeB));
break;
case "C":
assertTrue(node.getShortestPath().equals(shortestPathForNodeC));
break;
case "D":
assertTrue(node.getShortestPath().equals(shortestPathForNodeD));
break;
case "E":
assertTrue(node.getShortestPath().equals(shortestPathForNodeE));
break;
case "F":
assertTrue(node.getShortestPath().equals(shortestPathForNodeF));
break;
}
}
}
}

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spring-rest/pom.xml
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</properties> </properties>
<reporting>
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>findbugs-maven-plugin</artifactId>
<version>${findbugs-maven-plugin.version}</version>
<configuration>
<effort>Max</effort>
<omitVisitors>FindDeadLocalStores,FindNullDeref</omitVisitors>
</configuration>
</plugin>
</plugins>
</reporting>
</project> </project>