JAVA-32783 Split or move algorithms-miscellaneous-7 (#16317)

Co-authored-by: timis1 <noreplay@yahoo.com>
2024-04-10 01:03:56 +03:00
parent eea7bccf86
commit e812b299bd
13 changed files with 10 additions and 8 deletions
@@ -0,0 +1,57 @@
+package com.baeldung.algorithms.largestNumberRemovingK;
+
+import java.util.Stack;
+
+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());
+    }
+}
@@ -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);
+        }
+    }
+}
@@ -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);
+    }
+}
@@ -0,0 +1,129 @@
+package com.baeldung.algorithms.connect4;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class GameBoard {
+    private final List<List<Piece>> columns;
+
+    private final int rows;
+
+    public GameBoard(int columns, int rows) {
+        this.rows = rows;
+        this.columns = new ArrayList<>();
+
+        for (int i = 0; i < columns; ++i) {
+            this.columns.add(new ArrayList<>());
+        }
+    }
+
+    public int getRows() {
+        return rows;
+    }
+
+    public int getColumns() {
+        return columns.size();
+    }
+
+    public Piece getCell(int x, int y) {
+        assert(x >= 0 && x < getColumns());
+        assert(y >= 0 && y < getRows());
+
+        List<Piece> column = columns.get(x);
+
+        if (column.size() > y) {
+            return column.get(y);
+        } else {
+            return null;
+        }
+    }
+
+    public boolean move(int x, Piece player) {
+        assert(x >= 0 && x < getColumns());
+
+        List<Piece> column = columns.get(x);
+
+        if (column.size() >= this.rows) {
+            throw new IllegalArgumentException("That column is full");
+        }
+
+        column.add(player);
+
+        return checkWin(x, column.size() - 1, player);
+    }
+
+    private boolean checkWin(int x, int y, Piece player) {
+        // Vertical line
+        if (checkLine(x, y, 0, -1, player)) {
+            return true;
+        }
+
+        for (int offset = 0; offset < 4; ++offset) {
+            // Horizontal line
+            if (checkLine(x - 3 + offset, y, 1, 0, player)) {
+                return true;
+            }
+
+            // Leading diagonal
+            if (checkLine(x - 3 + offset, y + 3 - offset, 1, -1, player)) {
+                return true;
+            }
+
+            // Trailing diagonal
+            if (checkLine(x - 3 + offset, y - 3 + offset, 1, 1, player)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    private boolean checkLine(int x1, int y1, int xDiff, int yDiff, Piece player) {
+        for (int i = 0; i < 4; ++i) {
+            int x = x1 + (xDiff * i);
+            int y = y1 + (yDiff * i);
+
+            if (x < 0 || x > columns.size() - 1) {
+                return false;
+            }
+
+            if (y < 0 || y > rows - 1) {
+                return false;
+            }
+
+            if (player != getCell(x, y)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder result = new StringBuilder();
+
+        for (int y = getRows() - 1; y >= 0; --y) {
+            for (int x = 0; x < getColumns(); ++x) {
+                Piece piece = getCell(x, y);
+
+                result.append("|");
+                if (piece == null) {
+                    result.append(" ");
+                } else if (piece == Piece.PLAYER_1) {
+                    result.append("X");
+                } else if (piece == Piece.PLAYER_2) {
+                    result.append("O");
+                }
+            }
+
+            result.append("|\n");
+            for (int i = 0; i < getColumns(); ++i) {
+                result.append("+-");
+            }
+            result.append("+\n");
+        }
+
+        return result.toString();
+    }
+}
@@ -0,0 +1,40 @@
+package com.baeldung.algorithms.connect4;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class GameUnitTest {
+    @Test
+    public void blankGame() {
+        GameBoard gameBoard = new GameBoard(8, 6);
+
+        System.out.println(gameBoard);
+    }
+
+    @Test
+    public void playedGame() {
+        GameBoard gameBoard = new GameBoard(8, 6);
+
+        assertFalse(gameBoard.move(3, Piece.PLAYER_1));
+        assertFalse(gameBoard.move(2, Piece.PLAYER_2));
+
+        assertFalse(gameBoard.move(4, Piece.PLAYER_1));
+        assertFalse(gameBoard.move(3, Piece.PLAYER_2));
+
+        assertFalse(gameBoard.move(5, Piece.PLAYER_1));
+        assertFalse(gameBoard.move(6, Piece.PLAYER_2));
+
+        assertFalse(gameBoard.move(5, Piece.PLAYER_1));
+        assertFalse(gameBoard.move(4, Piece.PLAYER_2));
+
+        assertFalse(gameBoard.move(5, Piece.PLAYER_1));
+        assertFalse(gameBoard.move(5, Piece.PLAYER_2));
+
+        assertFalse(gameBoard.move(6, Piece.PLAYER_1));
+        assertTrue(gameBoard.move(4, Piece.PLAYER_2));
+
+        System.out.println(gameBoard);
+    }
+}
@@ -0,0 +1,6 @@
+package com.baeldung.algorithms.connect4;
+
+public enum Piece {
+    PLAYER_1,
+    PLAYER_2
+}
@@ -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));
+
+    }
+
+}
@@ -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));
+    }
+}
@@ -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);
+    }
+}
@@ -0,0 +1,85 @@
+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.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+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
+    }
+}