Merge remote-tracking branch 'upstream/master'

.gitignore

@@ -41,3 +41,5 @@ SpringDataInjectionDemo/.mvn/wrapper/maven-wrapper.properties
 spring-call-getters-using-reflection/.mvn/wrapper/maven-wrapper.properties
 
 spring-check-if-a-property-is-null/.mvn/wrapper/maven-wrapper.properties
+*.springBeans
+

README.md

@@ -23,4 +23,4 @@ Any IDE can be used to work with the projects, but if you're using Eclipse, cons
 
 CI - Jenkins
 ================================
-This tutorials project is being built **[>> HERE](https://rest-security.ci.cloudbees.com/job/tutorials/)**
+This tutorials project is being built **[>> HERE](https://rest-security.ci.cloudbees.com/job/github%20projects%20Jobs/job/tutorials/)**

algorithms/README.md

@@ -8,3 +8,4 @@
 - [Check If a Number Is Prime in Java](http://www.baeldung.com/java-prime-numbers)
 - [Example of Hill Climbing Algorithm](http://www.baeldung.com/java-hill-climbing-algorithm)
 - [Monte Carlo Tree Search for Tic-Tac-Toe Game](http://www.baeldung.com/java-monte-carlo-tree-search)
+- [String Search Algorithms for Large Texts](http://www.baeldung.com/java-full-text-search-algorithms)

algorithms/pom.xml

@@ -34,6 +34,11 @@
             <artifactId>jenetics</artifactId>
             <version>3.7.0</version>
         </dependency>
+        <dependency>
+            <groupId>org.jgrapht</groupId>
+            <artifactId>jgrapht-core</artifactId>
+            <version>1.0.1</version>
+        </dependency>
     </dependencies>
 
     <build>

algorithms/src/main/java/com/baeldung/algorithms/binarysearch/BinarySearch.java

@@ -0,0 +1,55 @@
+package com.baeldung.algorithms.binarysearch;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+public class BinarySearch {
+
+    public int runBinarySearchIteratively(int[] sortedArray, int key, int low, int high) {
+
+        int index = Integer.MAX_VALUE;
+
+        while (low <= high) {
+
+            int mid = (low + high) / 2;
+
+            if (sortedArray[mid] < key) {
+                low = mid + 1;
+            } else if (sortedArray[mid] > key) {
+                high = mid - 1;
+            } else if (sortedArray[mid] == key) {
+                index = mid;
+                break;
+            }
+        }
+        return index;
+    }
+
+    public int runBinarySearchRecursively(int[] sortedArray, int key, int low, int high) {
+
+        int middle = (low + high) / 2;
+        if (high < low) {
+            return -1;
+        }
+
+        if (key == sortedArray[middle]) {
+          return middle;
+        } else if (key < sortedArray[middle]) {
+          return runBinarySearchRecursively(sortedArray, key, low, middle - 1);
+        } else {
+          return runBinarySearchRecursively(sortedArray, key, middle + 1, high);
+        }
+    }
+
+    public int runBinarySearchUsingJavaArrays(int[] sortedArray, Integer key) {
+        int index = Arrays.binarySearch(sortedArray, key);
+        return index;
+    }
+
+    public int runBinarySearchUsingJavaCollections(List<Integer> sortedList, Integer key) {
+        int index = Collections.binarySearch(sortedList, key);
+        return index;
+    }
+
+}

algorithms/src/main/java/com/baeldung/algorithms/linkedlist/CycleDetectionBruteForce.java

@@ -0,0 +1,38 @@
+package com.baeldung.algorithms.linkedlist;
+
+public class CycleDetectionBruteForce {
+
+    public static <T> CycleDetectionResult<T> detectCycle(Node<T> head) {
+        if (head == null) {
+            return new CycleDetectionResult<>(false, null);
+        }
+
+        Node<T> it1 = head;
+        int nodesTraversedByOuter = 0;
+        while (it1 != null && it1.next != null) {
+            it1 = it1.next;
+            nodesTraversedByOuter++;
+
+            int x = nodesTraversedByOuter;
+            Node<T> it2 = head;
+            int noOfTimesCurrentNodeVisited = 0;
+
+            while (x > 0) {
+                it2 = it2.next;
+
+                if (it2 == it1) {
+                    noOfTimesCurrentNodeVisited++;
+                }
+
+                if (noOfTimesCurrentNodeVisited == 2) {
+                    return new CycleDetectionResult<>(true, it1);
+                }
+
+                x--;
+            }
+        }
+
+        return new CycleDetectionResult<>(false, null);
+    }
+
+}

algorithms/src/main/java/com/baeldung/algorithms/linkedlist/CycleDetectionByFastAndSlowIterators.java

@@ -0,0 +1,25 @@
+package com.baeldung.algorithms.linkedlist;
+
+public class CycleDetectionByFastAndSlowIterators {
+
+    public static <T> CycleDetectionResult<T> detectCycle(Node<T> head) {
+        if (head == null) {
+            return new CycleDetectionResult<>(false, null);
+        }
+
+        Node<T> slow = head;
+        Node<T> fast = head;
+
+        while (fast != null && fast.next != null) {
+            slow = slow.next;
+            fast = fast.next.next;
+
+            if (slow == fast) {
+                return new CycleDetectionResult<>(true, fast);
+            }
+        }
+
+        return new CycleDetectionResult<>(false, null);
+    }
+
+}

algorithms/src/main/java/com/baeldung/algorithms/linkedlist/CycleDetectionByHashing.java

@@ -0,0 +1,27 @@
+package com.baeldung.algorithms.linkedlist;
+
+import java.util.HashSet;
+import java.util.Set;
+
+public class CycleDetectionByHashing {
+
+    public static <T> CycleDetectionResult<T> detectCycle(Node<T> head) {
+        if (head == null) {
+            return new CycleDetectionResult<>(false, null);
+        }
+
+        Set<Node<T>> set = new HashSet<>();
+        Node<T> node = head;
+
+        while (node != null) {
+            if (set.contains(node)) {
+                return new CycleDetectionResult<>(true, node);
+            }
+            set.add(node);
+            node = node.next;
+        }
+
+        return new CycleDetectionResult<>(false, null);
+    }
+
+}

algorithms/src/main/java/com/baeldung/algorithms/linkedlist/CycleDetectionResult.java

@@ -0,0 +1,12 @@
+package com.baeldung.algorithms.linkedlist;
+
+public class CycleDetectionResult<T> {
+    boolean cycleExists;
+    Node<T> node;
+
+    public CycleDetectionResult(boolean cycleExists, Node<T> node) {
+        super();
+        this.cycleExists = cycleExists;
+        this.node = node;
+    }
+}

algorithms/src/main/java/com/baeldung/algorithms/linkedlist/CycleRemovalBruteForce.java

@@ -0,0 +1,56 @@
+package com.baeldung.algorithms.linkedlist;
+
+public class CycleRemovalBruteForce {
+
+    public static <T> boolean detectAndRemoveCycle(Node<T> head) {
+        CycleDetectionResult<T> result = CycleDetectionByFastAndSlowIterators.detectCycle(head);
+
+        if (result.cycleExists) {
+            removeCycle(result.node, head);
+        }
+
+        return result.cycleExists;
+    }
+
+    /**
+     * @param loopNodeParam - reference to the node where Flyods cycle 
+     * finding algorithm ends, i.e. the fast and the slow iterators
+     * meet.
+     * @param head - reference to the head of the list
+     */
+    private static <T> void removeCycle(Node<T> loopNodeParam, Node<T> head) {
+        Node<T> it = head;
+
+        while (it != null) {
+            if (isNodeReachableFromLoopNode(it, loopNodeParam)) {
+                Node<T> loopStart = it;
+                findEndNodeAndBreakCycle(loopStart);
+                break;
+            }
+            it = it.next;
+        }
+    }
+
+    private static <T> boolean isNodeReachableFromLoopNode(Node<T> it, Node<T> loopNodeParam) {
+        Node<T> loopNode = loopNodeParam;
+
+        do {
+            if (it == loopNode) {
+                return true;
+            }
+            loopNode = loopNode.next;
+        } while (loopNode.next != loopNodeParam);
+
+        return false;
+    }
+
+    private static <T> void findEndNodeAndBreakCycle(Node<T> loopStartParam) {
+        Node<T> loopStart = loopStartParam;
+
+        while (loopStart.next != loopStartParam) {
+            loopStart = loopStart.next;
+        }
+
+        loopStart.next = null;
+    }
+}

algorithms/src/main/java/com/baeldung/algorithms/linkedlist/CycleRemovalByCountingLoopNodes.java

@@ -0,0 +1,44 @@
+package com.baeldung.algorithms.linkedlist;
+
+public class CycleRemovalByCountingLoopNodes {
+
+    public static <T> boolean detectAndRemoveCycle(Node<T> head) {
+        CycleDetectionResult<T> result = CycleDetectionByFastAndSlowIterators.detectCycle(head);
+
+        if (result.cycleExists) {
+            removeCycle(result.node, head);
+        }
+
+        return result.cycleExists;
+    }
+
+    private static <T> void removeCycle(Node<T> loopNodeParam, Node<T> head) {
+        int cycleLength = calculateCycleLength(loopNodeParam);
+        Node<T> cycleLengthAdvancedIterator = head;
+        Node<T> it = head;
+
+        for (int i = 0; i < cycleLength; i++) {
+            cycleLengthAdvancedIterator = cycleLengthAdvancedIterator.next;
+        }
+
+        while (it.next != cycleLengthAdvancedIterator.next) {
+            it = it.next;
+            cycleLengthAdvancedIterator = cycleLengthAdvancedIterator.next;
+        }
+
+        cycleLengthAdvancedIterator.next = null;
+    }
+
+    private static <T> int calculateCycleLength(Node<T> loopNodeParam) {
+        Node<T> loopNode = loopNodeParam;
+        int length = 1;
+
+        while (loopNode.next != loopNodeParam) {
+            length++;
+            loopNode = loopNode.next;
+        }
+
+        return length;
+    }
+
+}

algorithms/src/main/java/com/baeldung/algorithms/linkedlist/CycleRemovalWithoutCountingLoopNodes.java

@@ -0,0 +1,27 @@
+package com.baeldung.algorithms.linkedlist;
+
+public class CycleRemovalWithoutCountingLoopNodes {
+
+    public static <T> boolean detectAndRemoveCycle(Node<T> head) {
+        CycleDetectionResult<T> result = CycleDetectionByFastAndSlowIterators.detectCycle(head);
+
+        if (result.cycleExists) {
+            removeCycle(result.node, head);
+        }
+
+        return result.cycleExists;
+    }
+
+    private static <T> void removeCycle(Node<T> meetingPointParam, Node<T> head) {
+        Node<T> loopNode = meetingPointParam;
+        Node<T> it = head;
+
+        while (loopNode.next != it.next) {
+            it = it.next;
+            loopNode = loopNode.next;
+        }
+
+        loopNode.next = null;
+    }
+
+}

algorithms/src/main/java/com/baeldung/algorithms/linkedlist/Node.java

@@ -0,0 +1,38 @@
+package com.baeldung.algorithms.linkedlist;
+
+public class Node<T> {
+    T data;
+    Node<T> next;
+
+    public static <T> Node<T> createNewNode(T data, Node<T> next) {
+        Node<T> node = new Node<T>();
+        node.data = data;
+        node.next = next;
+        return node;
+    }
+
+    public static <T> void traverseList(Node<T> root) {
+        if (root == null) {
+            return;
+        }
+
+        Node<T> node = root;
+        while (node != null) {
+            System.out.println(node.data);
+            node = node.next;
+        }
+    }
+
+    public static <T> Node<T> getTail(Node<T> root) {
+        if (root == null) {
+            return null;
+        }
+
+        Node<T> node = root;
+        while (node.next != null) {
+            node = node.next;
+        }
+        return node;
+    }
+
+}

algorithms/src/main/java/com/baeldung/algorithms/string/search/StringSearchAlgorithms.java

@@ -0,0 +1,194 @@
+package com.baeldung.algorithms.string.search;
+
+import java.math.BigInteger;
+import java.util.Random;
+
+public class StringSearchAlgorithms {
+    public static long getBiggerPrime(int m) {
+        BigInteger prime = BigInteger.probablePrime(getNumberOfBits(m) + 1, new Random());
+        return prime.longValue();
+    }
+
+    public static long getLowerPrime(long number) {
+        BigInteger prime = BigInteger.probablePrime(getNumberOfBits(number) - 1, new Random());
+        return prime.longValue();
+    }
+
+    private static int getNumberOfBits(final int number) {
+        return Integer.SIZE - Integer.numberOfLeadingZeros(number);
+    }
+
+    private static int getNumberOfBits(final long number) {
+        return Long.SIZE - Long.numberOfLeadingZeros(number);
+    }
+
+    public static int simpleTextSearch(char[] pattern, char[] text) {
+        int patternSize = pattern.length;
+        int textSize = text.length;
+
+        int i = 0;
+
+        while ((i + patternSize) <= textSize) {
+            int j = 0;
+            while (text[i + j] == pattern[j]) {
+                j += 1;
+                if (j >= patternSize)
+                    return i;
+            }
+            i += 1;
+        }
+
+        return -1;
+    }
+
+    public static int RabinKarpMethod(char[] pattern, char[] text) {
+        int patternSize = pattern.length; // m
+        int textSize = text.length; // n
+
+        long prime = getBiggerPrime(patternSize);
+
+        long r = 1;
+        for (int i = 0; i < patternSize - 1; i++) {
+            r *= 2;
+            r = r % prime;
+        }
+
+        long[] t = new long[textSize];
+        t[0] = 0;
+
+        long pfinger = 0;
+
+        for (int j = 0; j < patternSize; j++) {
+            t[0] = (2 * t[0] + text[j]) % prime;
+            pfinger = (2 * pfinger + pattern[j]) % prime;
+        }
+
+        int i = 0;
+        boolean passed = false;
+
+        int diff = textSize - patternSize;
+        for (i = 0; i <= diff; i++) {
+            if (t[i] == pfinger) {
+                passed = true;
+                for (int k = 0; k < patternSize; k++) {
+                    if (text[i + k] != pattern[k]) {
+                        passed = false;
+                        break;
+                    }
+                }
+
+                if (passed) {
+                    return i;
+                }
+            }
+
+            if (i < diff) {
+                long value = 2 * (t[i] - r * text[i]) + text[i + patternSize];
+                t[i + 1] = ((value % prime) + prime) % prime;
+            }
+        }
+        return -1;
+
+    }
+
+    public static int KnuthMorrisPrattSearch(char[] pattern, char[] text) {
+        int patternSize = pattern.length; // m
+        int textSize = text.length; // n
+
+        int i = 0, j = 0;
+
+        int[] shift = KnuthMorrisPrattShift(pattern);
+
+        while ((i + patternSize) <= textSize) {
+            while (text[i + j] == pattern[j]) {
+                j += 1;
+                if (j >= patternSize)
+                    return i;
+            }
+
+            if (j > 0) {
+                i += shift[j - 1];
+                j = Math.max(j - shift[j - 1], 0);
+            } else {
+                i++;
+                j = 0;
+            }
+        }
+        return -1;
+    }
+
+    public static int[] KnuthMorrisPrattShift(char[] pattern) {
+        int patternSize = pattern.length;
+
+        int[] shift = new int[patternSize];
+        shift[0] = 1;
+
+        int i = 1, j = 0;
+
+        while ((i + j) < patternSize) {
+            if (pattern[i + j] == pattern[j]) {
+                shift[i + j] = i;
+                j++;
+            } else {
+                if (j == 0)
+                    shift[i] = i + 1;
+
+                if (j > 0) {
+                    i = i + shift[j - 1];
+                    j = Math.max(j - shift[j - 1], 0);
+                } else {
+                    i = i + 1;
+                    j = 0;
+                }
+            }
+        }
+        return shift;
+    }
+
+    public static int BoyerMooreHorspoolSimpleSearch(char[] pattern, char[] text) {
+        int patternSize = pattern.length;
+        int textSize = text.length;
+
+        int i = 0, j = 0;
+
+        while ((i + patternSize) <= textSize) {
+            j = patternSize - 1;
+            while (text[i + j] == pattern[j]) {
+                j--;
+                if (j < 0)
+                    return i;
+            }
+            i++;
+        }
+        return -1;
+    }
+
+    public static int BoyerMooreHorspoolSearch(char[] pattern, char[] text) {
+
+        int shift[] = new int[256];
+
+        for (int k = 0; k < 256; k++) {
+            shift[k] = pattern.length;
+        }
+
+        for (int k = 0; k < pattern.length - 1; k++) {
+            shift[pattern[k]] = pattern.length - 1 - k;
+        }
+
+        int i = 0, j = 0;
+
+        while ((i + pattern.length) <= text.length) {
+            j = pattern.length - 1;
+
+            while (text[i + j] == pattern[j]) {
+                j -= 1;
+                if (j < 0)
+                    return i;
+            }
+
+            i = i + shift[text[i + pattern.length - 1]];
+
+        }
+        return -1;
+    }
+}

algorithms/src/test/java/algorithms/StringSearchAlgorithmsTest.java

@@ -0,0 +1,25 @@
+package algorithms;
+
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import com.baeldung.algorithms.string.search.StringSearchAlgorithms;
+
+public class StringSearchAlgorithmsTest {
+	
+	
+	@Test
+	public void testStringSearchAlgorithms(){
+		String text = "This is some nice text.";
+		String pattern = "some";
+		
+		int realPosition = text.indexOf(pattern);
+        Assert.assertTrue(realPosition == StringSearchAlgorithms.simpleTextSearch(pattern.toCharArray(), text.toCharArray()));
+        Assert.assertTrue(realPosition == StringSearchAlgorithms.RabinKarpMethod(pattern.toCharArray(), text.toCharArray()));
+        Assert.assertTrue(realPosition == StringSearchAlgorithms.KnuthMorrisPrattSearch(pattern.toCharArray(), text.toCharArray()));
+        Assert.assertTrue(realPosition == StringSearchAlgorithms.BoyerMooreHorspoolSimpleSearch(pattern.toCharArray(), text.toCharArray()));
+        Assert.assertTrue(realPosition == StringSearchAlgorithms.BoyerMooreHorspoolSearch(pattern.toCharArray(), text.toCharArray()));
+	}
+
+}

algorithms/src/test/java/algorithms/binarysearch/BinarySearchTest.java

@@ -0,0 +1,43 @@
+package algorithms.binarysearch;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.Assert;
+import org.junit.Test;
+import com.baeldung.algorithms.binarysearch.BinarySearch;
+
+public class BinarySearchTest {
+
+    int[] sortedArray = { 0, 1, 2, 3, 4, 5, 5, 6, 7, 8, 9, 9 };
+    int key = 6;
+    int expectedIndexForSearchKey = 7;
+    int low = 0;
+    int high = sortedArray.length - 1;
+    List<Integer> sortedList = Arrays.asList(0, 1, 2, 3, 4, 5, 5, 6, 7, 8, 9, 9);
+    
+    @Test
+    public void givenASortedArrayOfIntegers_whenBinarySearchRunIterativelyForANumber_thenGetIndexOfTheNumber() {
+        BinarySearch binSearch = new BinarySearch();
+        Assert.assertEquals(expectedIndexForSearchKey, binSearch.runBinarySearchIteratively(sortedArray, key, low, high));
+    }
+
+    @Test
+    public void givenASortedArrayOfIntegers_whenBinarySearchRunRecursivelyForANumber_thenGetIndexOfTheNumber() {
+        BinarySearch binSearch = new BinarySearch();
+        Assert.assertEquals(expectedIndexForSearchKey, binSearch.runBinarySearchRecursively(sortedArray, key, low, high));
+    }
+    
+    @Test
+    public void givenASortedArrayOfIntegers_whenBinarySearchRunUsingArraysClassStaticMethodForANumber_thenGetIndexOfTheNumber() {
+        BinarySearch binSearch = new BinarySearch();
+        Assert.assertEquals(expectedIndexForSearchKey, binSearch.runBinarySearchUsingJavaArrays(sortedArray, key));
+    }
+    
+    @Test
+    public void givenASortedListOfIntegers_whenBinarySearchRunUsingCollectionsClassStaticMethodForANumber_thenGetIndexOfTheNumber() {
+        BinarySearch binSearch = new BinarySearch();
+        Assert.assertEquals(expectedIndexForSearchKey, binSearch.runBinarySearchUsingJavaCollections(sortedList, key));
+    }
+    
+}

algorithms/src/test/java/com/baeldung/algorithms/linkedlist/CycleDetectionBruteForceTest.java

@@ -0,0 +1,23 @@
+package com.baeldung.algorithms.linkedlist;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+@RunWith(value = Parameterized.class)
+public class CycleDetectionBruteForceTest extends CycleDetectionTestBase {
+    boolean cycleExists;
+    Node<Integer> head;
+
+    public CycleDetectionBruteForceTest(Node<Integer> head, boolean cycleExists) {
+        super();
+        this.cycleExists = cycleExists;
+        this.head = head;
+    }
+
+    @Test
+    public void givenList_detectLoop() {
+        Assert.assertEquals(cycleExists, CycleDetectionBruteForce.detectCycle(head).cycleExists);
+    }
+}

algorithms/src/test/java/com/baeldung/algorithms/linkedlist/CycleDetectionByFastAndSlowIteratorsTest.java

@@ -0,0 +1,23 @@
+package com.baeldung.algorithms.linkedlist;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+@RunWith(value = Parameterized.class)
+public class CycleDetectionByFastAndSlowIteratorsTest extends CycleDetectionTestBase {
+    boolean cycleExists;
+    Node<Integer> head;
+
+    public CycleDetectionByFastAndSlowIteratorsTest(Node<Integer> head, boolean cycleExists) {
+        super();
+        this.cycleExists = cycleExists;
+        this.head = head;
+    }
+
+    @Test
+    public void givenList_detectLoop() {
+        Assert.assertEquals(cycleExists, CycleDetectionByFastAndSlowIterators.detectCycle(head).cycleExists);
+    }
+}

algorithms/src/test/java/com/baeldung/algorithms/linkedlist/CycleDetectionByHashingTest.java

@@ -0,0 +1,23 @@
+package com.baeldung.algorithms.linkedlist;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+@RunWith(value = Parameterized.class)
+public class CycleDetectionByHashingTest extends CycleDetectionTestBase {
+    boolean cycleExists;
+    Node<Integer> head;
+
+    public CycleDetectionByHashingTest(Node<Integer> head, boolean cycleExists) {
+        super();
+        this.cycleExists = cycleExists;
+        this.head = head;
+    }
+
+    @Test
+    public void givenList_detectLoop() {
+        Assert.assertEquals(cycleExists, CycleDetectionByHashing.detectCycle(head).cycleExists);
+    }
+}

algorithms/src/test/java/com/baeldung/algorithms/linkedlist/CycleDetectionTestBase.java

@@ -0,0 +1,62 @@
+package com.baeldung.algorithms.linkedlist;
+
+import java.util.Arrays;
+import java.util.Collection;
+
+import org.junit.runners.Parameterized.Parameters;
+
+public class CycleDetectionTestBase {
+
+    @Parameters
+    public static Collection<Object[]> getLists() {
+        return Arrays.asList(new Object[][] { 
+            { createList(), false }, 
+            { createListWithLoop(), true },
+            { createListWithFullCycle(), true }, 
+            { createListWithSingleNodeInCycle(), true } 
+        });
+    }
+
+    public static Node<Integer> createList() {
+        Node<Integer> root = Node.createNewNode(10, null);
+
+        for (int i = 9; i >= 1; --i) {
+            Node<Integer> current = Node.createNewNode(i, root);
+            root = current;
+        }
+
+        return root;
+    }
+
+    public static Node<Integer> createListWithLoop() {
+        Node<Integer> node = createList();
+        createLoop(node);
+        return node;
+    }
+
+    public static Node<Integer> createListWithFullCycle() {
+        Node<Integer> head = createList();
+        Node<Integer> tail = Node.getTail(head);
+        tail.next = head;
+        return head;
+    }
+
+    public static Node<Integer> createListWithSingleNodeInCycle() {
+        Node<Integer> head = createList();
+        Node<Integer> tail = Node.getTail(head);
+        tail.next = tail;
+        return head;
+    }
+
+    public static void createLoop(Node<Integer> root) {
+        Node<Integer> tail = Node.getTail(root);
+
+        Node<Integer> middle = root;
+        for (int i = 1; i <= 4; i++) {
+            middle = middle.next;
+        }
+
+        tail.next = middle;
+    }
+
+}

algorithms/src/test/java/com/baeldung/algorithms/linkedlist/CycleRemovalBruteForceTest.java

@@ -0,0 +1,24 @@
+package com.baeldung.algorithms.linkedlist;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+@RunWith(value = Parameterized.class)
+public class CycleRemovalBruteForceTest extends CycleDetectionTestBase {
+    boolean cycleExists;
+    Node<Integer> head;
+
+    public CycleRemovalBruteForceTest(Node<Integer> head, boolean cycleExists) {
+        super();
+        this.cycleExists = cycleExists;
+        this.head = head;
+    }
+
+    @Test
+    public void givenList_ifLoopExists_thenDetectAndRemoveLoop() {
+        Assert.assertEquals(cycleExists, CycleRemovalBruteForce.detectAndRemoveCycle(head));
+        Assert.assertFalse(CycleDetectionByFastAndSlowIterators.detectCycle(head).cycleExists);
+    }
+}

algorithms/src/test/java/com/baeldung/algorithms/linkedlist/CycleRemovalByCountingLoopNodesTest.java

@@ -0,0 +1,24 @@
+package com.baeldung.algorithms.linkedlist;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+@RunWith(value = Parameterized.class)
+public class CycleRemovalByCountingLoopNodesTest extends CycleDetectionTestBase {
+    boolean cycleExists;
+    Node<Integer> head;
+
+    public CycleRemovalByCountingLoopNodesTest(Node<Integer> head, boolean cycleExists) {
+        super();
+        this.cycleExists = cycleExists;
+        this.head = head;
+    }
+
+    @Test
+    public void givenList_ifLoopExists_thenDetectAndRemoveLoop() {
+        Assert.assertEquals(cycleExists, CycleRemovalByCountingLoopNodes.detectAndRemoveCycle(head));
+        Assert.assertFalse(CycleDetectionByFastAndSlowIterators.detectCycle(head).cycleExists);
+    }
+}

algorithms/src/test/java/com/baeldung/algorithms/linkedlist/CycleRemovalWithoutCountingLoopNodesTest.java

@@ -0,0 +1,24 @@
+package com.baeldung.algorithms.linkedlist;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+@RunWith(value = Parameterized.class)
+public class CycleRemovalWithoutCountingLoopNodesTest extends CycleDetectionTestBase {
+    boolean cycleExists;
+    Node<Integer> head;
+
+    public CycleRemovalWithoutCountingLoopNodesTest(Node<Integer> head, boolean cycleExists) {
+        super();
+        this.cycleExists = cycleExists;
+        this.head = head;
+    }
+
+    @Test
+    public void givenList_ifLoopExists_thenDetectAndRemoveLoop() {
+        Assert.assertEquals(cycleExists, CycleRemovalWithoutCountingLoopNodes.detectAndRemoveCycle(head));
+        Assert.assertFalse(CycleDetectionByFastAndSlowIterators.detectCycle(head).cycleExists);
+    }
+}

algorithms/src/test/java/com/baeldung/jgrapht/CompleteGraphTest.java

@@ -0,0 +1,38 @@
+package com.baeldung.jgrapht;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.List;
+
+import org.jgrapht.VertexFactory;
+import org.jgrapht.alg.HamiltonianCycle;
+import org.jgrapht.generate.CompleteGraphGenerator;
+import org.jgrapht.graph.DefaultEdge;
+import org.jgrapht.graph.SimpleWeightedGraph;
+import org.junit.Before;
+import org.junit.Test;
+
+public class CompleteGraphTest {
+
+    static SimpleWeightedGraph<String, DefaultEdge> completeGraph;
+    static int size = 10;
+
+    @Before
+    public void createCompleteGraph() {
+        completeGraph = new SimpleWeightedGraph<>(DefaultEdge.class);
+        CompleteGraphGenerator<String, DefaultEdge> completeGenerator = new CompleteGraphGenerator<String, DefaultEdge>(size);
+        VertexFactory<String> vFactory = new VertexFactory<String>() {
+            private int id = 0;
+            public String createVertex() {
+                return "v" + id++;
+            }
+        };
+        completeGenerator.generateGraph(completeGraph, vFactory, null);
+    }
+
+    @Test
+    public void givenCompleteGraph_whenGetHamiltonianCyclePath_thenGetVerticeListInSequence() {
+        List<String> verticeList = HamiltonianCycle.getApproximateOptimalForCompleteGraph(completeGraph);
+        assertEquals(verticeList.size(), completeGraph.vertexSet().size());
+    }
+}

algorithms/src/test/java/com/baeldung/jgrapht/DirectedGraphTests.java

@@ -0,0 +1,95 @@
+package com.baeldung.jgrapht;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.IntStream;
+
+import org.jgrapht.DirectedGraph;
+import org.jgrapht.GraphPath;
+import org.jgrapht.alg.CycleDetector;
+import org.jgrapht.alg.KosarajuStrongConnectivityInspector;
+import org.jgrapht.alg.interfaces.StrongConnectivityAlgorithm;
+import org.jgrapht.alg.shortestpath.AllDirectedPaths;
+import org.jgrapht.alg.shortestpath.BellmanFordShortestPath;
+import org.jgrapht.alg.shortestpath.DijkstraShortestPath;
+import org.jgrapht.graph.DefaultDirectedGraph;
+import org.jgrapht.graph.DefaultEdge;
+import org.jgrapht.graph.DirectedSubgraph;
+import org.jgrapht.traverse.BreadthFirstIterator;
+import org.jgrapht.traverse.DepthFirstIterator;
+import org.junit.Before;
+import org.junit.Test;
+
+public class DirectedGraphTests {
+    DirectedGraph<String, DefaultEdge> directedGraph;
+
+    @Before
+    public void createDirectedGraph() {
+        directedGraph = new DefaultDirectedGraph<String, DefaultEdge>(DefaultEdge.class);
+        IntStream.range(1, 10).forEach(i -> {
+            directedGraph.addVertex("v" + i);
+        });
+        directedGraph.addEdge("v1", "v2");
+        directedGraph.addEdge("v2", "v4");
+        directedGraph.addEdge("v4", "v3");
+        directedGraph.addEdge("v3", "v1");
+        directedGraph.addEdge("v5", "v4");
+        directedGraph.addEdge("v5", "v6");
+        directedGraph.addEdge("v6", "v7");
+        directedGraph.addEdge("v7", "v5");
+        directedGraph.addEdge("v8", "v5");
+        directedGraph.addEdge("v9", "v8");
+    }
+
+    @Test
+    public void givenDirectedGraph_whenGetStronglyConnectedSubgraphs_thenPathExistsBetweenStronglyconnectedVertices() {
+        StrongConnectivityAlgorithm<String, DefaultEdge> scAlg = new KosarajuStrongConnectivityInspector<>(directedGraph);
+        List<DirectedSubgraph<String, DefaultEdge>> stronglyConnectedSubgraphs = scAlg.stronglyConnectedSubgraphs();
+        List<String> stronglyConnectedVertices = new ArrayList<>(stronglyConnectedSubgraphs.get(3).vertexSet());
+
+        String randomVertex1 = stronglyConnectedVertices.get(0);
+        String randomVertex2 = stronglyConnectedVertices.get(3);
+        AllDirectedPaths<String, DefaultEdge> allDirectedPaths = new AllDirectedPaths<>(directedGraph);
+
+        List<GraphPath<String, DefaultEdge>> possiblePathList = allDirectedPaths.getAllPaths(randomVertex1, randomVertex2, false, stronglyConnectedVertices.size());
+        assertTrue(possiblePathList.size() > 0);
+    }
+
+    @Test
+    public void givenDirectedGraphWithCycle_whenCheckCycles_thenDetectCycles() {
+        CycleDetector<String, DefaultEdge> cycleDetector = new CycleDetector<String, DefaultEdge>(directedGraph);
+        assertTrue(cycleDetector.detectCycles());
+        Set<String> cycleVertices = cycleDetector.findCycles();
+        assertTrue(cycleVertices.size() > 0);
+    }
+
+    @Test
+    public void givenDirectedGraph_whenCreateInstanceDepthFirstIterator_thenGetIterator() {
+        DepthFirstIterator depthFirstIterator = new DepthFirstIterator<>(directedGraph);
+        assertNotNull(depthFirstIterator);
+    }
+
+    @Test
+    public void givenDirectedGraph_whenCreateInstanceBreadthFirstIterator_thenGetIterator() {
+        BreadthFirstIterator breadthFirstIterator = new BreadthFirstIterator<>(directedGraph);
+        assertNotNull(breadthFirstIterator);
+    }
+
+    @Test
+    public void givenDirectedGraph_whenGetDijkstraShortestPath_thenGetNotNullPath() {
+        DijkstraShortestPath dijkstraShortestPath = new DijkstraShortestPath(directedGraph);
+        List<String> shortestPath = dijkstraShortestPath.getPath("v1", "v4").getVertexList();
+        assertNotNull(shortestPath);
+    }
+
+    @Test
+    public void givenDirectedGraph_whenGetBellmanFordShortestPath_thenGetNotNullPath() {
+        BellmanFordShortestPath bellmanFordShortestPath = new BellmanFordShortestPath(directedGraph);
+        List<String> shortestPath = bellmanFordShortestPath.getPath("v1", "v4").getVertexList();
+        assertNotNull(shortestPath);
+    }
+}

algorithms/src/test/java/com/baeldung/jgrapht/EulerianCircuitTest.java

@@ -0,0 +1,42 @@
+package com.baeldung.jgrapht;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import java.util.stream.IntStream;
+
+import org.jgrapht.GraphPath;
+import org.jgrapht.alg.cycle.HierholzerEulerianCycle;
+import org.jgrapht.graph.DefaultEdge;
+import org.jgrapht.graph.SimpleWeightedGraph;
+import org.junit.Before;
+import org.junit.Test;
+
+public class EulerianCircuitTest {
+    SimpleWeightedGraph<String, DefaultEdge> simpleGraph;
+
+    @Before
+    public void createGraphWithEulerianCircuit() {
+        simpleGraph = new SimpleWeightedGraph<>(DefaultEdge.class);
+        IntStream.range(1, 6).forEach(i -> {
+            simpleGraph.addVertex("v" + i);
+        });
+        IntStream.range(1, 6).forEach(i -> {
+            int endVertexNo = (i + 1) > 5 ? 1 : i + 1;
+            simpleGraph.addEdge("v" + i, "v" + endVertexNo);
+        });
+    }
+
+    @Test
+    public void givenGraph_whenCheckEluerianCycle_thenGetResult() {
+        HierholzerEulerianCycle eulerianCycle = new HierholzerEulerianCycle<>();
+        assertTrue(eulerianCycle.isEulerian(simpleGraph));
+    }
+
+    @Test
+    public void givenGraphWithEulerianCircuit_whenGetEulerianCycle_thenGetGraphPath() {
+        HierholzerEulerianCycle eulerianCycle = new HierholzerEulerianCycle<>();
+        GraphPath path = eulerianCycle.getEulerianCycle(simpleGraph);
+        assertTrue(path.getEdgeList().containsAll(simpleGraph.edgeSet()));
+    }
+}

animal-sniffer-mvn-plugin/pom.xml

@@ -0,0 +1,57 @@
+<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/maven-v4_0_0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>com.baeldung</groupId>
+  <artifactId>animal-sniffer-mvn-plugin</artifactId>
+  <packaging>jar</packaging>
+  <version>1.0-SNAPSHOT</version>
+  <name>example-animal-sniffer-mvn-plugin</name>
+  <url>http://maven.apache.org</url>
+  
+  <properties>
+        <maven-compiler-plugin.version>3.6.0</maven-compiler-plugin.version>	
+    </properties>
+	
+  <dependencies>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <version>3.8.1</version>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+  <build>
+        <plugins>
+				 <plugin>
+				  <artifactId>maven-compiler-plugin</artifactId>
+				  <version>3.7.0</version>
+				  <configuration>
+					<source>1.6</source>
+					<target>1.6</target>
+				  </configuration>
+				</plugin>
+				<plugin>
+					<groupId>org.codehaus.mojo</groupId>
+					<artifactId>animal-sniffer-maven-plugin</artifactId>
+					<version>1.16</version>
+					<configuration>
+						<signature>
+							<groupId>org.codehaus.mojo.signature</groupId>
+							<artifactId>java16</artifactId>
+							<version>1.0</version>
+						</signature>
+					</configuration>
+					<executions>
+						<execution>
+							<id>animal-sniffer</id>
+							<phase>verify</phase>	
+							<goals>
+								<goal>check</goal>
+							</goals>
+						</execution>
+					</executions>
+				</plugin>
+        </plugins>
+
+    </build>
+</project>

animal-sniffer-mvn-plugin/src/main/java/com/baeldung/App.java

@@ -0,0 +1,16 @@
+package com.baeldung;
+
+//import java.nio.charset.StandardCharsets;
+
+/**
+ * Hello world!
+ *
+ */
+public class App 
+{
+    public static void main( String[] args )
+    {
+        System.out.println( "Hello World!" );
+		//System.out.println(StandardCharsets.UTF_8.name());
+    }
+}

animal-sniffer-mvn-plugin/src/test/java/com/baeldung/AppTest.java

@@ -0,0 +1,40 @@
+package com.baeldung;
+
+import junit.framework.Test;
+import junit.framework.TestCase;
+import junit.framework.TestSuite;
+
+/**
+ * Unit test for simple App.
+ */
+public class AppTest 
+    extends TestCase
+{
+    /**
+     * Create the test case
+     *
+     * @param testName name of the test case
+     */
+    public AppTest( String testName )
+    {
+        super( testName );
+    }
+
+    /**
+     * @return the suite of tests being tested
+     */
+    public static Test suite()
+    {
+        return new TestSuite( AppTest.class );
+    }
+
+    /**
+     * Rigourous Test :-)
+     */
+    public void testApp()
+    {
+		
+        assertTrue( true );
+		
+    }
+}

apache-cayenne/pom.xml

@@ -0,0 +1,59 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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>
+
+	<artifactId>apache-cayenne</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<packaging>jar</packaging>
+
+	<name>apache-cayenne</name>
+	<description>Introduction to Apache Cayenne</description>
+
+	<parent>
+		<groupId>com.baeldung</groupId>
+		<artifactId>parent-modules</artifactId>
+		<version>1.0.0-SNAPSHOT</version>
+	</parent>
+
+	<properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+		<java.version>1.8</java.version>
+		<mysql.connector.version>5.1.44</mysql.connector.version>
+		<cayenne.version>4.0.M5</cayenne.version>
+		<junit.version>4.12</junit.version>
+	</properties>
+
+	<dependencies>
+		<dependency>
+			<groupId>org.apache.cayenne</groupId>
+			<artifactId>cayenne-server</artifactId>
+			<version>${cayenne.version}</version>
+		</dependency>
+		<dependency>
+			<groupId>mysql</groupId>
+			<artifactId>mysql-connector-java</artifactId>
+			<version>${mysql.connector.version}</version>
+			<scope>runtime</scope>
+		</dependency>
+
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+	<build>
+		<plugins>
+            <plugin>
+                <groupId>org.apache.cayenne.plugins</groupId>
+                <artifactId>cayenne-modeler-maven-plugin</artifactId>
+                <version>${cayenne.version}</version>
+            </plugin>
+		</plugins>
+	</build>
+
+</project>