Merge branch 'master' into BAEL-7513-Merge-overlapping-intervals-in-collection

algorithms-modules/algorithms-miscellaneous-1/pom.xml

@@ -19,11 +19,6 @@
             <artifactId>commons-math3</artifactId>
             <version>${commons-math3.version}</version>
         </dependency>
-        <dependency>
-            <groupId>com.google.guava</groupId>
-            <artifactId>guava</artifactId>
-            <version>${guava.version}</version>
-        </dependency>
         <dependency>
             <groupId>commons-codec</groupId>
             <artifactId>commons-codec</artifactId>

algorithms-modules/algorithms-miscellaneous-5/pom.xml

@@ -29,11 +29,7 @@
             <artifactId>tradukisto</artifactId>
             <version>${tradukisto.version}</version>
         </dependency>
-        <dependency>
-            <groupId>com.google.guava</groupId>
-            <artifactId>guava</artifactId>
-            <version>${guava.version}</version>
-        </dependency>
+
         <!-- API, java.xml.bind module -->
         <dependency>
             <groupId>jakarta.xml.bind</groupId>

algorithms-modules/algorithms-miscellaneous-7/README.md

@@ -7,4 +7,11 @@
 - [Rotate Arrays in Java](https://www.baeldung.com/java-rotate-arrays)
 - [Find Missing Number From a Given Array in Java](https://www.baeldung.com/java-array-find-missing-number)
 - [Calculate Weighted Mean in Java](https://www.baeldung.com/java-compute-weighted-average)
+- [Check if Two Strings Are Rotations of Each Other](https://www.baeldung.com/java-string-check-strings-rotations)
+- [Find the Largest Prime Under the Given Number in Java](https://www.baeldung.com/java-largest-prime-lower-threshold)
+- [Count the Number of Unique Digits in an Integer using Java](https://www.baeldung.com/java-int-count-unique-digits)
+- [Generate Juggler Sequence in Java](https://www.baeldung.com/java-generate-juggler-sequence)
+- [Finding the Parent of a Node in a Binary Search Tree with Java](https://www.baeldung.com/java-find-parent-node-binary-search-tree)
+- [Check if a Number Is a Happy Number in Java](https://www.baeldung.com/java-happy-sad-number-test)
+- [Find the Largest Number Possible After Removing k Digits of a Number](https://www.baeldung.com/java-find-largest-number-remove-k-digits)
 - More articles: [[<-- prev]](/algorithms-miscellaneous-6)

algorithms-modules/algorithms-miscellaneous-7/src/main/java/com/baeldung/algorithms/largestNumberRemovingK/LargestNumberRemoveKDigits.java

@@ -0,0 +1,57 @@
+package com.baeldung.algorithms.largestNumberRemovingK;
+
+import java.util.*;
+
+public class LargestNumberRemoveKDigits {
+    public static int findLargestNumberUsingArithmetic(int num, int k) {
+        for (int j = 0; j < k; j++) {
+
+            int result = 0;
+            int i = 1;
+
+            while (num / i > 0) {
+                int temp = (num / (i * 10))
+                        * i
+                        + (num % i);
+                i *= 10;
+
+                result = Math.max(result, temp);
+            }
+            num = result;
+        }
+
+        return num;
+    }
+
+    public static int findLargestNumberUsingStack(int num, int k) {
+        String numStr = Integer.toString(num);
+        int length = numStr.length();
+
+        if (k == length) return 0;
+
+        Stack<Character> stack = new Stack<>();
+
+        for (int i = 0; i < length; i++) {
+            char digit = numStr.charAt(i);
+
+            while (k > 0 && !stack.isEmpty() && stack.peek() < digit) {
+                stack.pop();
+                k--;
+            }
+
+            stack.push(digit);
+        }
+
+        while (k > 0) {
+            stack.pop();
+            k--;
+        }
+
+        StringBuilder result = new StringBuilder();
+        while (!stack.isEmpty()) {
+            result.insert(0, stack.pop());
+        }
+
+        return Integer.parseInt(result.toString());
+    }
+}

algorithms-modules/algorithms-miscellaneous-7/src/main/java/com/baeldung/algorithms/parentnodebinarytree/ParentKeeperTreeNode.java

@@ -0,0 +1,54 @@
+package com.baeldung.algorithms.parentnodebinarytree;
+
+import java.util.Objects;
+
+public class ParentKeeperTreeNode {
+
+    int value;
+    ParentKeeperTreeNode parent;
+    ParentKeeperTreeNode left;
+    ParentKeeperTreeNode right;
+
+    public ParentKeeperTreeNode(int value) {
+        this.value = value;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        ParentKeeperTreeNode treeNode = (ParentKeeperTreeNode) o;
+        return value == treeNode.value;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(value);
+    }
+
+    public void insert(int value) {
+        insert(this, value);
+    }
+
+    private void insert(ParentKeeperTreeNode currentNode, final int value) {
+        if (currentNode.left == null && value < currentNode.value) {
+            currentNode.left = new ParentKeeperTreeNode(value);
+            currentNode.left.parent = currentNode;
+            return;
+        }
+
+        if (currentNode.right == null && value > currentNode.value) {
+            currentNode.right = new ParentKeeperTreeNode(value);
+            currentNode.right.parent = currentNode;
+            return;
+        }
+
+        if (value > currentNode.value) {
+            insert(currentNode.right, value);
+        }
+
+        if (value < currentNode.value) {
+            insert(currentNode.left, value);
+        }
+    }
+}

algorithms-modules/algorithms-miscellaneous-7/src/main/java/com/baeldung/algorithms/parentnodebinarytree/TreeNode.java

@@ -0,0 +1,107 @@
+package com.baeldung.algorithms.parentnodebinarytree;
+
+import java.util.Deque;
+import java.util.LinkedList;
+import java.util.NoSuchElementException;
+import java.util.Objects;
+
+import static java.lang.String.format;
+
+public class TreeNode {
+    int value;
+    TreeNode left;
+    TreeNode right;
+
+    public TreeNode(int value) {
+        this.value = value;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        TreeNode treeNode = (TreeNode) o;
+        return value == treeNode.value;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(value);
+    }
+
+    public void insert(int value) {
+        insert(this, value);
+    }
+
+    private void insert(TreeNode currentNode, final int value) {
+        if (currentNode.left == null && value < currentNode.value) {
+            currentNode.left = new TreeNode(value);
+            return;
+        }
+
+        if (currentNode.right == null && value > currentNode.value) {
+            currentNode.right = new TreeNode(value);
+            return;
+        }
+
+        if (value > currentNode.value) {
+            insert(currentNode.right, value);
+        }
+
+        if (value < currentNode.value) {
+            insert(currentNode.left, value);
+        }
+    }
+
+    public TreeNode parent(int target) throws NoSuchElementException {
+        return parent(this, new TreeNode(target));
+    }
+
+    private TreeNode parent(TreeNode current, TreeNode target) throws NoSuchElementException {
+        if (target.equals(current) || current == null) {
+            throw new NoSuchElementException(format("No parent node found for 'target.value=%s' " +
+                            "The target is not in the tree or the target is the topmost root node.",
+                    target.value));
+        }
+
+        if (target.equals(current.left) || target.equals(current.right)) {
+            return current;
+        }
+
+        return parent(target.value < current.value ? current.left : current.right, target);
+    }
+
+    public TreeNode iterativeParent(int target) {
+        return iterativeParent(this, new TreeNode(target));
+    }
+
+    private TreeNode iterativeParent(TreeNode current, TreeNode target) {
+        Deque<TreeNode> parentCandidates = new LinkedList<>();
+
+        String notFoundMessage = format("No parent node found for 'target.value=%s' " +
+                        "The target is not in the tree or the target is the topmost root node.",
+                target.value);
+
+        if (target.equals(current)) {
+            throw new NoSuchElementException(notFoundMessage);
+        }
+
+        while (current != null || !parentCandidates.isEmpty()) {
+
+            while (current != null) {
+                parentCandidates.addFirst(current);
+                current = current.left;
+            }
+
+            current = parentCandidates.pollFirst();
+
+            if (target.equals(current.left) || target.equals(current.right)) {
+                return current;
+            }
+
+            current = current.right;
+        }
+
+        throw new NoSuchElementException(notFoundMessage);
+    }
+}

algorithms-modules/algorithms-miscellaneous-7/src/main/java/com/baeldung/algorithms/stringrotation/StringRotation.java

@@ -0,0 +1,123 @@
+package com.baeldung.algorithms.stringrotation;
+
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Queue;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+public class StringRotation {
+
+    public static boolean doubledOriginContainsRotation(String origin, String rotation) {
+        if (origin.length() == rotation.length()) {
+            return origin.concat(origin)
+              .contains(rotation);
+        }
+
+        return false;
+    }
+
+    public static boolean isRotationUsingCommonStartWithOrigin(String origin, String rotation) {
+
+        if (origin.length() == rotation.length()) {
+
+            List<Integer> indexes = IntStream.range(0, origin.length())
+              .filter(i -> rotation.charAt(i) == origin.charAt(0))
+              .boxed()
+              .collect(Collectors.toList());
+
+            for (int startingAt : indexes) {
+                if (isRotation(startingAt, rotation, origin)) {
+                    return true;
+                }
+            }
+        }
+
+        return false;
+    }
+
+    static boolean isRotation(int startingAt, String rotation, String origin) {
+
+        for (int i = 0; i < origin.length(); i++) {
+            if (rotation.charAt((startingAt + i) % origin.length()) != origin.charAt(i)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    public static boolean isRotationUsingQueue(String origin, String rotation) {
+
+        if (origin.length() == rotation.length()) {
+            return checkWithQueue(origin, rotation);
+        }
+
+        return false;
+    }
+
+    static boolean checkWithQueue(String origin, String rotation) {
+
+        if (origin.length() == rotation.length()) {
+
+            Queue<Character> originQueue = getCharactersQueue(origin);
+
+            Queue<Character> rotationQueue = getCharactersQueue(rotation);
+
+            int k = rotation.length();
+            while (k > 0 && null != rotationQueue.peek()) {
+                k--;
+                char ch = rotationQueue.peek();
+                rotationQueue.remove();
+                rotationQueue.add(ch);
+                if (rotationQueue.equals(originQueue)) {
+                    return true;
+                }
+            }
+        }
+
+        return false;
+    }
+
+    static Queue<Character> getCharactersQueue(String origin) {
+        return origin.chars()
+          .mapToObj(c -> (char) c)
+          .collect(Collectors.toCollection(LinkedList::new));
+    }
+
+    public static boolean isRotationUsingSuffixAndPrefix(String origin, String rotation) {
+
+        if (origin.length() == rotation.length()) {
+            return checkPrefixAndSuffix(origin, rotation);
+        }
+
+        return false;
+    }
+
+    static boolean checkPrefixAndSuffix(String origin, String rotation) {
+        if (origin.length() == rotation.length()) {
+
+            for (int i = 0; i < origin.length(); i++) {
+                if (origin.charAt(i) == rotation.charAt(0)) {
+                    if (checkRotationPrefixWithOriginSuffix(origin, rotation, i)) {
+                        if (checkOriginPrefixWithRotationSuffix(origin, rotation, i))
+                            return true;
+                    }
+                }
+            }
+
+        }
+
+        return false;
+    }
+
+    private static boolean checkRotationPrefixWithOriginSuffix(String origin, String rotation, int i) {
+        return origin.substring(i)
+          .equals(rotation.substring(0, origin.length() - i));
+    }
+
+    private static boolean checkOriginPrefixWithRotationSuffix(String origin, String rotation, int i) {
+        return origin.substring(0, i)
+          .equals(rotation.substring(origin.length() - i));
+    }
+}

algorithms-modules/algorithms-miscellaneous-7/src/main/java/com/baeldung/algorithms/uniquedigit/UniqueDigitCounter.java

@@ -0,0 +1,36 @@
+package com.baeldung.algorithms.uniquedigit;
+
+import java.util.HashSet;
+import java.util.Set;
+
+public class UniqueDigitCounter {
+
+    public static int countWithSet(int number) {
+        number = Math.abs(number);
+        Set<Character> uniqueDigits = new HashSet<>();
+        String numberStr = String.valueOf(number);
+        for (char digit : numberStr.toCharArray()) {
+            uniqueDigits.add(digit);
+        }
+        return uniqueDigits.size();
+    }
+
+    public static int countWithBitManipulation(int number) {
+        if (number == 0) {
+            return 1;
+        }
+        number = Math.abs(number);
+        int mask = 0;
+        while (number > 0) {
+            int digit = number % 10;
+            mask |= 1 << digit;
+            number /= 10;
+        }
+        return Integer.bitCount(mask);
+    }
+
+    public static long countWithStreamApi(int number) {
+        return String.valueOf(Math.abs(number)).chars().distinct().count();
+    }
+
+}

algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/happynumber/HappyNumberUnitTest.java

@@ -0,0 +1,82 @@
+package com.baeldung.algorithms.happynumber;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import org.junit.jupiter.api.Test;
+
+class HappyNumberDecider {
+
+    public static boolean isHappyNumber(int n) {
+        Set<Integer> checkedNumbers = new HashSet<>();
+        while (true) {
+            n = sumDigitsSquare(n);
+            if (n == 1) {
+                return true;
+            }
+            if (checkedNumbers.contains(n)) {
+                return false;
+            }
+            checkedNumbers.add(n);
+        }
+    }
+
+    public static boolean isHappyNumberFloyd(int n) {
+        int slow = n;
+        int fast = n;
+        do {
+            slow = sumDigitsSquare(slow);
+            fast = sumDigitsSquare(sumDigitsSquare(fast));
+        } while (slow != fast);
+
+        return slow == 1;
+    }
+
+    private static int sumDigitsSquare(int n) {
+        int squareSum = 0;
+        while (n != 0) {
+            squareSum += (n % 10) * (n % 10);
+            n /= 10;
+        }
+        return squareSum;
+    }
+}
+
+public class HappyNumberUnitTest {
+
+    @Test
+    void whenUsingIsHappyNumber_thenGetTheExpectedResult() {
+        assertTrue(HappyNumberDecider.isHappyNumber(7));
+        assertTrue(HappyNumberDecider.isHappyNumber(10));
+        assertTrue(HappyNumberDecider.isHappyNumber(13));
+        assertTrue(HappyNumberDecider.isHappyNumber(19));
+        assertTrue(HappyNumberDecider.isHappyNumber(23));
+
+        assertFalse(HappyNumberDecider.isHappyNumber(4));
+        assertFalse(HappyNumberDecider.isHappyNumber(6));
+        assertFalse(HappyNumberDecider.isHappyNumber(11));
+        assertFalse(HappyNumberDecider.isHappyNumber(15));
+        assertFalse(HappyNumberDecider.isHappyNumber(20));
+
+    }
+
+    @Test
+    void whenUsingIsHappyNumber2_thenGetTheExpectedResult() {
+        assertTrue(HappyNumberDecider.isHappyNumberFloyd(7));
+        assertTrue(HappyNumberDecider.isHappyNumberFloyd(10));
+        assertTrue(HappyNumberDecider.isHappyNumberFloyd(13));
+        assertTrue(HappyNumberDecider.isHappyNumberFloyd(19));
+        assertTrue(HappyNumberDecider.isHappyNumberFloyd(23));
+
+        assertFalse(HappyNumberDecider.isHappyNumberFloyd(4));
+        assertFalse(HappyNumberDecider.isHappyNumberFloyd(6));
+        assertFalse(HappyNumberDecider.isHappyNumberFloyd(11));
+        assertFalse(HappyNumberDecider.isHappyNumberFloyd(15));
+        assertFalse(HappyNumberDecider.isHappyNumberFloyd(20));
+
+    }
+
+}

algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/jugglersequence/JugglerSequenceUnitTest.java

@@ -0,0 +1,68 @@
+package com.baeldung.algorithms.jugglersequence;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+class JugglerSequenceGenerator {
+
+    public static List<Integer> byLoop(int n) {
+        if (n <= 0) {
+            throw new IllegalArgumentException("The initial integer must be greater than zero.");
+        }
+        List<Integer> seq = new ArrayList<>();
+        int current = n;
+        seq.add(current);
+        while (current != 1) {
+            int next = (int) (Math.sqrt(current) * (current % 2 == 0 ? 1 : current));
+            seq.add(next);
+            current = next;
+        }
+        return seq;
+    }
+
+    public static List<Integer> byRecursion(int n) {
+        if (n <= 0) {
+            throw new IllegalArgumentException("The initial integer must be greater than zero.");
+        }
+        List<Integer> seq = new ArrayList<>();
+        fillSeqRecursively(n, seq);
+        return seq;
+    }
+
+    private static void fillSeqRecursively(int current, List<Integer> result) {
+        result.add(current);
+        if (current == 1) {
+            return;
+        }
+        int next = (int) (Math.sqrt(current) * (current % 2 == 0 ? 1 : current));
+        fillSeqRecursively(next, result);
+    }
+}
+
+public class JugglerSequenceUnitTest {
+
+    @Test
+    void whenGeneratingJugglerSeqUsingLoop_thenGetTheExpectedResult() {
+        assertThrows(IllegalArgumentException.class, () -> JugglerSequenceGenerator.byLoop(0));
+        assertEquals(List.of(3, 5, 11, 36, 6, 2, 1), JugglerSequenceGenerator.byLoop(3));
+        assertEquals(List.of(4, 2, 1), JugglerSequenceGenerator.byLoop(4));
+        assertEquals(List.of(9, 27, 140, 11, 36, 6, 2, 1), JugglerSequenceGenerator.byLoop(9));
+        assertEquals(List.of(21, 96, 9, 27, 140, 11, 36, 6, 2, 1), JugglerSequenceGenerator.byLoop(21));
+        assertEquals(List.of(42, 6, 2, 1), JugglerSequenceGenerator.byLoop(42));
+    }
+
+    @Test
+    void whenGeneratingJugglerSeqUsingRecursion_thenGetTheExpectedResult() {
+        assertThrows(IllegalArgumentException.class, () -> JugglerSequenceGenerator.byRecursion(0));
+        assertEquals(List.of(3, 5, 11, 36, 6, 2, 1), JugglerSequenceGenerator.byRecursion(3));
+        assertEquals(List.of(4, 2, 1), JugglerSequenceGenerator.byRecursion(4));
+        assertEquals(List.of(9, 27, 140, 11, 36, 6, 2, 1), JugglerSequenceGenerator.byRecursion(9));
+        assertEquals(List.of(21, 96, 9, 27, 140, 11, 36, 6, 2, 1), JugglerSequenceGenerator.byRecursion(21));
+        assertEquals(List.of(42, 6, 2, 1), JugglerSequenceGenerator.byRecursion(42));
+    }
+}

algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/largestNumberRemovingK/LargestNumberRemoveKDigitsUnitTest.java

@@ -0,0 +1,25 @@
+package com.baeldung.algorithms.largestNumberRemovingK;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class LargestNumberRemoveKDigitsUnitTest {
+
+    @Test
+    public void givenNumber_UsingArithmeticRemoveKDigits_thenReturnLargestNumber(){
+        Assertions.assertEquals(LargestNumberRemoveKDigits.findLargestNumberUsingArithmetic(9461, 1), 961);
+        Assertions.assertEquals(LargestNumberRemoveKDigits.findLargestNumberUsingArithmetic(463, 2), 6);
+        Assertions.assertEquals(LargestNumberRemoveKDigits.findLargestNumberUsingArithmetic(98625410, 6), 98);
+        Assertions.assertEquals(LargestNumberRemoveKDigits.findLargestNumberUsingArithmetic(20, 2), 0);
+        Assertions.assertEquals(LargestNumberRemoveKDigits.findLargestNumberUsingArithmetic(98989, 4), 9);
+    }
+
+    @Test
+    public void givenNumber_UsingStackRemoveKDigits_thenReturnLargestNumber(){
+        Assertions.assertEquals(LargestNumberRemoveKDigits.findLargestNumberUsingStack(9461, 1), 961);
+        Assertions.assertEquals(LargestNumberRemoveKDigits.findLargestNumberUsingStack(463, 2), 6);
+        Assertions.assertEquals(LargestNumberRemoveKDigits.findLargestNumberUsingStack(98625410, 6), 98);
+        Assertions.assertEquals(LargestNumberRemoveKDigits.findLargestNumberUsingStack(20, 2), 0);
+        Assertions.assertEquals(LargestNumberRemoveKDigits.findLargestNumberUsingStack(98989, 4), 9);
+    }
+}

algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/parentnodebinarytree/BinaryTreeParentNodeFinderUnitTest.java

@@ -0,0 +1,83 @@
+package com.baeldung.algorithms.parentnodebinarytree;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.NoSuchElementException;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class BinaryTreeParentNodeFinderUnitTest {
+
+    private TreeNode subject;
+
+    @BeforeEach
+    void setUp() {
+        subject = new TreeNode(8);
+        subject.insert(5);
+        subject.insert(12);
+        subject.insert(3);
+        subject.insert(7);
+        subject.insert(1);
+        subject.insert(4);
+        subject.insert(11);
+        subject.insert(14);
+        subject.insert(13);
+        subject.insert(16);
+    }
+
+    @Test
+    void givenBinaryTree_whenFindParentNode_thenReturnCorrectParentNode() {
+        assertEquals(8, subject.parent(5).value);
+        assertEquals(5, subject.parent(3).value);
+        assertEquals(5, subject.parent(7).value);
+        assertEquals(3, subject.parent(4).value);
+        assertEquals(3, subject.parent(1).value);
+        assertEquals(8, subject.parent(12).value);
+        assertEquals(12, subject.parent(14).value);
+        assertEquals(12, subject.parent(11).value);
+        assertEquals(14, subject.parent(16).value);
+        assertEquals(14, subject.parent(13).value);
+        assertThrows(NoSuchElementException.class, () -> subject.parent(1231));
+        assertThrows(NoSuchElementException.class, () -> subject.parent(8));
+    }
+
+    @Test
+    void givenBinaryTree_whenFindParentNodeIteratively_thenReturnCorrectParentNode() {
+        assertEquals(8, subject.iterativeParent(5).value);
+        assertEquals(5, subject.iterativeParent(3).value);
+        assertEquals(5, subject.iterativeParent(7).value);
+        assertEquals(3, subject.iterativeParent(4).value);
+        assertEquals(3, subject.iterativeParent(1).value);
+        assertEquals(8, subject.iterativeParent(12).value);
+        assertEquals(12, subject.iterativeParent(14).value);
+        assertEquals(12, subject.iterativeParent(11).value);
+        assertEquals(14, subject.iterativeParent(16).value);
+        assertEquals(14, subject.iterativeParent(13).value);
+        assertThrows(NoSuchElementException.class, () -> subject.iterativeParent(1231));
+        assertThrows(NoSuchElementException.class, () -> subject.iterativeParent(8));
+    }
+
+    @Test
+    void givenParentKeeperBinaryTree_whenGetParent_thenReturnCorrectParent() {
+        ParentKeeperTreeNode subject = new ParentKeeperTreeNode(8);
+        subject.insert(5);
+        subject.insert(12);
+        subject.insert(3);
+        subject.insert(7);
+        subject.insert(1);
+        subject.insert(4);
+        subject.insert(11);
+        subject.insert(14);
+        subject.insert(13);
+        subject.insert(16);
+
+        assertNull(subject.parent);
+        assertEquals(8, subject.left.parent.value);
+        assertEquals(8, subject.right.parent.value);
+        assertEquals(5, subject.left.left.parent.value);
+        assertEquals(5, subject.left.right.parent.value);
+
+        // tests for other nodes
+    }
+}

algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/stringrotation/StringRotationUnitTest.java

@@ -0,0 +1,61 @@
+package com.baeldung.algorithms.stringrotation;
+
+import static com.baeldung.algorithms.stringrotation.StringRotation.doubledOriginContainsRotation;
+import static com.baeldung.algorithms.stringrotation.StringRotation.isRotationUsingCommonStartWithOrigin;
+import static com.baeldung.algorithms.stringrotation.StringRotation.isRotationUsingQueue;
+import static com.baeldung.algorithms.stringrotation.StringRotation.isRotationUsingSuffixAndPrefix;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+class StringRotationUnitTest {
+
+    @Test
+    void givenOriginAndRotationInput_whenCheckIfOriginContainsRotation_thenIsRotation() {
+        assertTrue(doubledOriginContainsRotation("abcd", "cdab"));
+        assertTrue(doubledOriginContainsRotation("abcd", "abcd"));
+    }
+
+    @Test
+    void givenOriginAndRotationInput_whenCheckIfOriginContainsRotation_thenNoRotation() {
+        assertFalse(doubledOriginContainsRotation("abcd", "bbbb"));
+        assertFalse(doubledOriginContainsRotation("abcd", "abcde"));
+    }
+
+    @Test
+    void givenOriginAndRotationInput_whenCheckingCommonStartWithOrigin_thenIsRotation() {
+        assertTrue(isRotationUsingCommonStartWithOrigin("abcd", "cdab"));
+        assertTrue(isRotationUsingCommonStartWithOrigin("abcd", "abcd"));
+    }
+
+    @Test
+    void givenOriginAndRotationInput_whenCheckingCommonStartWithOrigin_thenNoRotation() {
+        assertFalse(isRotationUsingCommonStartWithOrigin("abcd", "bbbb"));
+        assertFalse(isRotationUsingCommonStartWithOrigin("abcd", "abcde"));
+    }
+
+    @Test
+    void givenOriginAndRotationInput_whenCheckingUsingQueues_thenIsRotation() {
+        assertTrue(isRotationUsingQueue("abcd", "cdab"));
+        assertTrue(isRotationUsingQueue("abcd", "abcd"));
+    }
+
+    @Test
+    void givenOriginAndRotationInput_whenCheckingUsingQueues_thenNoRotation() {
+        assertFalse(isRotationUsingQueue("abcd", "bbbb"));
+        assertFalse(isRotationUsingQueue("abcd", "abcde"));
+    }
+
+    @Test
+    void givenOriginAndRotationInput_whenCheckingUsingSuffixAndPrefix_thenIsRotation() {
+        assertTrue(isRotationUsingSuffixAndPrefix("abcd", "cdab"));
+        assertTrue(isRotationUsingSuffixAndPrefix("abcd", "abcd"));
+    }
+
+    @Test
+    void givenOriginAndRotationInput_whenCheckingUsingSuffixAndPrefix_thenNoRotation() {
+        assertFalse(isRotationUsingSuffixAndPrefix("abcd", "bbbb"));
+        assertFalse(isRotationUsingSuffixAndPrefix("abcd", "abcde"));
+    }
+}

algorithms-modules/algorithms-miscellaneous-7/src/test/java/com/baeldung/algorithms/uniquedigit/UniqueDigitCounterUnitTest.java

@@ -0,0 +1,38 @@
+package com.baeldung.algorithms.uniquedigit;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class UniqueDigitCounterUnitTest {
+
+    @Test
+    public void givenNotNegativeNumber_whenCountUniqueDigits_thenCorrectCount() {
+        assertEquals(3, UniqueDigitCounter.countWithSet(122333));
+        assertEquals(1, UniqueDigitCounter.countWithSet(0));
+        assertEquals(2, UniqueDigitCounter.countWithSet(101));
+
+        assertEquals(3, UniqueDigitCounter.countWithBitManipulation(122333));
+        assertEquals(1, UniqueDigitCounter.countWithBitManipulation(0));
+        assertEquals(2, UniqueDigitCounter.countWithBitManipulation(101));
+
+        assertEquals(3, UniqueDigitCounter.countWithStreamApi(122333));
+        assertEquals(1, UniqueDigitCounter.countWithStreamApi(0));
+        assertEquals(2, UniqueDigitCounter.countWithStreamApi(101));
+    }
+
+    @Test
+    public void givenNegativeNumber_whenCountUniqueDigits_thenCorrectCount() {
+        assertEquals(3, UniqueDigitCounter.countWithSet(-122333));
+        assertEquals(3, UniqueDigitCounter.countWithBitManipulation(-122333));
+        assertEquals(3, UniqueDigitCounter.countWithStreamApi(-122333));
+    }
+
+    @Test
+    public void givenLargeNumber_whenCountUniqueDigits_thenCorrectCount() {
+        assertEquals(2, UniqueDigitCounter.countWithSet(1000000000));
+        assertEquals(2, UniqueDigitCounter.countWithBitManipulation(1000000000));
+        assertEquals(2, UniqueDigitCounter.countWithStreamApi(1000000000));
+    }
+
+}

algorithms-modules/algorithms-miscellaneous-8/README.md

@@ -0,0 +1,2 @@
+### Relevant Articles: 
+- [Vigenère Cipher in Java](https://www.baeldung.com/java-vigenere-cipher)

algorithms-modules/algorithms-miscellaneous-8/pom.xml

@@ -0,0 +1,16 @@
+<?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>algorithms-miscellaneous-8</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>algorithms-miscellaneous-8</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>algorithms-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+</project>

algorithms-modules/algorithms-miscellaneous-8/src/test/java/com/baeldung/algorithms/vigenere/VigenereCipher.java

@@ -0,0 +1,69 @@
+package com.baeldung.algorithms.vigenere;
+
+public class VigenereCipher {
+    private final String characters;
+
+    public VigenereCipher() {
+        this("ABCDEFGHIJKLMNOPQRSTUVWXYZ");
+    }
+
+    public VigenereCipher(String characters) {
+        this.characters = characters;
+    }
+
+    public String encode(String input, String key) {
+        String result = "";
+
+        int keyPosition = 0;
+        for (char c : input.toCharArray()) {
+            char k = key.charAt(keyPosition % key.length());
+
+            int charIndex = characters.indexOf(c);
+            int keyIndex = characters.indexOf(k);
+
+            if (charIndex >= 0) {
+                if (keyIndex >= 0) {
+                    int newCharIndex = (charIndex + keyIndex + 1) % characters.length();
+                    c = characters.charAt(newCharIndex);
+
+                }
+
+                keyPosition++;
+            }
+
+            result += c;
+        }
+
+        return result;
+    }
+
+    public String decode(String input, String key) {
+        String result = "";
+
+        int keyPosition = 0;
+        for (char c : input.toCharArray()) {
+            char k = key.charAt(keyPosition % key.length());
+
+            int charIndex = characters.indexOf(c);
+            int keyIndex = characters.indexOf(k);
+
+            if (charIndex >= 0) {
+                if (keyIndex >= 0) {
+                    int newCharIndex = charIndex - keyIndex - 1;
+                    if (newCharIndex < 0) {
+                        newCharIndex = characters.length() + newCharIndex;
+                    }
+                    c = characters.charAt(newCharIndex);
+
+                }
+
+                keyPosition++;
+            }
+
+            result += c;
+        }
+
+        return result;
+    }
+
+}

algorithms-modules/algorithms-miscellaneous-8/src/test/java/com/baeldung/algorithms/vigenere/VigenereCipherUnitTest.java

@@ -0,0 +1,76 @@
+package com.baeldung.algorithms.vigenere;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class VigenereCipherUnitTest {
+
+    @Test
+    void encodeBaeldung() {
+        VigenereCipher cipher = new VigenereCipher();
+        String output = cipher.encode("BAELDUNG", "HELLO");
+
+        Assertions.assertEquals("JFQXSCSS", output);
+    }
+
+    @Test
+    void encodeBaeldungMixedCharacters() {
+        VigenereCipher cipher = new VigenereCipher("JQFVHPWORZSLNMKYCGBUXIEDTA");
+        String output = cipher.encode("BAELDUNG", "HELLO");
+
+        Assertions.assertEquals("DERDPTZV", output);
+    }
+
+    @Test
+    void encodeArticleTitle() {
+        VigenereCipher cipher = new VigenereCipher();
+        String output = cipher.encode("VIGENERE CIPHER IN JAVA", "BAELDUNG");
+
+        Assertions.assertEquals("XJLQRZFL EJUTIM WU LBAM", output);
+    }
+
+    @Test
+    void encodeArticleTitleMoreCharacters() {
+        VigenereCipher cipher = new VigenereCipher("ABCDEFGHIJKLMNOPQRSTUVWXYZ ");
+        String output = cipher.encode("VIGENERE CIPHER IN JAVA", "BAELDUNG");
+
+        Assertions.assertEquals("XJLQRZELBDNALZEGKOEVEPO", output);
+    }
+
+    @Test
+    void decodeBaeldung() {
+        VigenereCipher cipher = new VigenereCipher();
+        String output = cipher.decode("JFQXSCSS", "HELLO");
+
+        Assertions.assertEquals("BAELDUNG", output);
+    }
+
+    @Test
+    void decodeBaeldungMixedCharacters() {
+        VigenereCipher cipher = new VigenereCipher("JQFVHPWORZSLNMKYCGBUXIEDTA");
+        String output = cipher.decode("DERDPTZV", "HELLO");
+
+        Assertions.assertEquals("BAELDUNG", output);
+    }
+
+    @Test
+    void decodeArticleTitleMoreCharacters() {
+        VigenereCipher cipher = new VigenereCipher("ABCDEFGHIJKLMNOPQRSTUVWXYZ ");
+        String output = cipher.decode("XJLQRZELBDNALZEGKOEVEPO", "BAELDUNG");
+
+        Assertions.assertEquals("VIGENERE CIPHER IN JAVA", output);
+    }
+
+    @Test
+    void encodeDecodeBaeldung() {
+        VigenereCipher cipher = new VigenereCipher();
+
+        String input = "BAELDUNG";
+        String key = "HELLO";
+
+        String encoded = cipher.encode(input, key);
+        String decoded = cipher.decode(encoded, key);
+
+        Assertions.assertEquals(input, decoded);
+    }
+}

algorithms-modules/pom.xml

@@ -22,6 +22,7 @@
         <module>algorithms-miscellaneous-5</module>
         <module>algorithms-miscellaneous-6</module>
         <module>algorithms-miscellaneous-7</module>
+        <module>algorithms-miscellaneous-8</module>
         <module>algorithms-searching</module>
         <module>algorithms-sorting</module>
         <module>algorithms-sorting-2</module>
@@ -34,4 +35,4 @@
         <tradukisto.version>1.0.1</tradukisto.version>
     </properties>
 
-</project>
+</project>