Merge branch 'master' of https://github.com/sankethl27/Java

Author: sankethl27

DIRECTORY.md

@@ -170,6 +170,7 @@
               * [LinkedQueue](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/queues/LinkedQueue.java)
               * [PriorityQueues](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/queues/PriorityQueues.java)
               * [Queue](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/queues/Queue.java)
+              * [QueueByTwoStacks](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/queues/QueueByTwoStacks.java)
             * stacks
               * [NodeStack](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/stacks/NodeStack.java)
               * [ReverseStack](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/stacks/ReverseStack.java)
@@ -207,7 +208,7 @@
               * [SplayTree](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/SplayTree.java)
               * [Treap](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/Treap.java)
               * [TreeRandomNode](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/TreeRandomNode.java)
-              * [TrieImp](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/TrieImp.java)
+              * [Trie](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/Trie.java)
               * [VerticalOrderTraversal](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/VerticalOrderTraversal.java)
               * [ZigzagTraversal](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/datastructures/trees/ZigzagTraversal.java)
           * devutils
@@ -377,6 +378,7 @@
             * [PrimeFactorization](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/PrimeFactorization.java)
             * [PronicNumber](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/PronicNumber.java)
             * [PythagoreanTriple](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/PythagoreanTriple.java)
+            * [QuadraticEquationSolver](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/QuadraticEquationSolver.java)
             * [ReverseNumber](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/ReverseNumber.java)
             * [RomanNumeralUtil](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/RomanNumeralUtil.java)
             * [SecondMinMax](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/maths/SecondMinMax.java)
@@ -476,6 +478,7 @@
           * searches
             * [BinarySearch](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/searches/BinarySearch.java)
             * [BinarySearch2dArray](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/searches/BinarySearch2dArray.java)
+            * [BM25InvertedIndex](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/searches/BM25InvertedIndex.java)
             * [BreadthFirstSearch](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/searches/BreadthFirstSearch.java)
             * [DepthFirstSearch](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/searches/DepthFirstSearch.java)
             * [ExponentalSearch](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/searches/ExponentalSearch.java)
@@ -730,6 +733,7 @@
               * [GenericArrayListQueueTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/queues/GenericArrayListQueueTest.java)
               * [LinkedQueueTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/queues/LinkedQueueTest.java)
               * [PriorityQueuesTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/queues/PriorityQueuesTest.java)
+              * [QueueByTwoStacksTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/queues/QueueByTwoStacksTest.java)
               * [QueueTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/queues/QueueTest.java)
             * stacks
               * [LinkedListStackTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/stacks/LinkedListStackTest.java)
@@ -755,7 +759,7 @@
               * [SplayTreeTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/SplayTreeTest.java)
               * [TreapTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/TreapTest.java)
               * [TreeTestUtils](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/TreeTestUtils.java)
-              * [TrieImpTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/TrieImpTest.java)
+              * [TrieTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/TrieTest.java)
               * [VerticalOrderTraversalTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/VerticalOrderTraversalTest.java)
               * [ZigzagTraversalTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/ZigzagTraversalTest.java)
           * divideandconquer
@@ -886,6 +890,7 @@
             * [PrimeFactorizationTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/PrimeFactorizationTest.java)
             * [PronicNumberTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/PronicNumberTest.java)
             * [PythagoreanTripleTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/PythagoreanTripleTest.java)
+            * [QuadraticEquationSolverTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/QuadraticEquationSolverTest.java)
             * [ReverseNumberTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/ReverseNumberTest.java)
             * [SecondMinMaxTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/SecondMinMaxTest.java)
             * [SieveOfEratosthenesTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/SieveOfEratosthenesTest.java)
@@ -951,6 +956,7 @@
             * [SRTFSchedulingTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/scheduling/SRTFSchedulingTest.java)
           * searches
             * [BinarySearch2dArrayTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/BinarySearch2dArrayTest.java)
+            * [BM25InvertedIndexTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/BM25InvertedIndexTest.java)
             * [BreadthFirstSearchTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/BreadthFirstSearchTest.java)
             * [DepthFirstSearchTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/DepthFirstSearchTest.java)
             * [HowManyTimesRotatedTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/HowManyTimesRotatedTest.java)

pom.xml

@@ -63,7 +63,7 @@
         <plugins>
             <plugin>
                 <artifactId>maven-surefire-plugin</artifactId>
-                <version>3.5.0</version>
+                <version>3.5.1</version>
                 <configuration>
                     <forkNode implementation="org.apache.maven.plugin.surefire.extensions.SurefireForkNodeFactory"/>
                 </configuration>

src/main/java/com/thealgorithms/datastructures/queues/QueueByTwoStacks.java

@@ -0,0 +1,87 @@
+package com.thealgorithms.datastructures.queues;
+
+import java.util.NoSuchElementException;
+import java.util.Stack;
+
+/**
+ * A queue implementation using two stacks. This class provides methods to
+ * enqueue (add) elements to the end of the queue and dequeue (remove)
+ * elements from the front, while utilizing two internal stacks to manage
+ * the order of elements.
+ *
+ * @param <T> The type of elements held in this queue.
+ */
+public class QueueByTwoStacks<T> {
+
+    private final Stack<T> enqueueStk;
+    private final Stack<T> dequeueStk;
+
+    /**
+     * Constructor that initializes two empty stacks for the queue.
+     * The `enqueueStk` is used to push elements when enqueuing, and
+     * the `dequeueStk` is used to pop elements when dequeuing.
+     */
+    public QueueByTwoStacks() {
+        enqueueStk = new Stack<>();
+        dequeueStk = new Stack<>();
+    }
+
+    /**
+     * Adds an element to the end of the queue. This method pushes the element
+     * onto the `enqueueStk`.
+     *
+     * @param item The element to be added to the queue.
+     */
+    public void put(T item) {
+        enqueueStk.push(item);
+    }
+
+    /**
+     * Removes and returns the element at the front of the queue.
+     * If `dequeueStk` is empty, it transfers all elements from
+     * `enqueueStk` to `dequeueStk` to maintain the correct FIFO
+     * (First-In-First-Out) order before popping.
+     *
+     * @return The element at the front of the queue.
+     * @throws NoSuchElementException If the queue is empty.
+     */
+    public T get() {
+        if (dequeueStk.isEmpty()) {
+            while (!enqueueStk.isEmpty()) {
+                dequeueStk.push(enqueueStk.pop());
+            }
+        }
+        if (dequeueStk.isEmpty()) {
+            throw new NoSuchElementException("Queue is empty");
+        }
+        return dequeueStk.pop();
+    }
+
+    /**
+     * Returns the total number of elements currently in the queue.
+     * This is the sum of the sizes of both stacks.
+     *
+     * @return The number of elements in the queue.
+     */
+    public int size() {
+        return enqueueStk.size() + dequeueStk.size();
+    }
+
+    /**
+     * Returns a string representation of the queue, showing the elements
+     * in the correct order (from front to back).
+     * The `dequeueStk` is first cloned, and then all elements from the
+     * `enqueueStk` are added to the cloned stack in reverse order to
+     * represent the queue accurately.
+     *
+     * @return A string representation of the queue.
+     */
+    @Override
+    public String toString() {
+        Stack<T> tempStack = (Stack<T>) dequeueStk.clone();
+        while (!enqueueStk.isEmpty()) {
+            tempStack.push(enqueueStk.pop());
+        }
+        return "Queue(" + tempStack + ")";
+    }
+}

src/main/java/com/thealgorithms/datastructures/trees/TrieImp.java renamed to src/main/java/com/thealgorithms/datastructures/trees/Trie.java

@@ -1,5 +1,28 @@
 package com.thealgorithms.datastructures.trees;
 
+import java.util.HashMap;
+
+/**
+ * Represents a Trie Node that stores a character and pointers to its children.
+ * Each node has a hashmap which can point to all possible characters.
+ * Each node also has a boolean value to indicate if it is the end of a word.
+ */
+class TrieNode {
+    char value;
+    HashMap<Character, TrieNode> child;
+    boolean end;
+
+    /**
+     * Constructor to initialize a TrieNode with an empty hashmap
+     * and set end to false.
+     */
+    TrieNode(char value) {
+        this.value = value;
+        this.child = new HashMap<>();
+        this.end = false;
+    }
+}
+
 /**
  * Trie Data structure implementation without any libraries.
  * <p>
@@ -14,36 +37,20 @@
  * possible character.
  *
  * @author <a href="https://github.com/dheeraj92">Dheeraj Kumar Barnwal</a>
+ * @author <a href="https://github.com/sailok">Sailok Chinta</a>
  */
-public class TrieImp {
 
-    /**
-     * Represents a Trie Node that stores a character and pointers to its children.
-     * Each node has an array of 26 children (one for each letter from 'a' to 'z').
-     */
-    public class TrieNode {
-
-        TrieNode[] child;
-        boolean end;
-
-        /**
-         * Constructor to initialize a TrieNode with an empty child array
-         * and set end to false.
-         */
-        public TrieNode() {
-            child = new TrieNode[26];
-            end = false;
-        }
-    }
+public class Trie {
+    private static final char ROOT_NODE_VALUE = '*';
 
     private final TrieNode root;
 
     /**
      * Constructor to initialize the Trie.
      * The root node is created but doesn't represent any character.
      */
-    public TrieImp() {
-        root = new TrieNode();
+    public Trie() {
+        root = new TrieNode(ROOT_NODE_VALUE);
     }
 
     /**
@@ -57,13 +64,15 @@ public TrieImp() {
     public void insert(String word) {
         TrieNode currentNode = root;
         for (int i = 0; i < word.length(); i++) {
-            TrieNode node = currentNode.child[word.charAt(i) - 'a'];
+            TrieNode node = currentNode.child.getOrDefault(word.charAt(i), null);
+
             if (node == null) {
-                node = new TrieNode();
-                currentNode.child[word.charAt(i) - 'a'] = node;
+                node = new TrieNode(word.charAt(i));
+                currentNode.child.put(word.charAt(i), node);
             }
             currentNode = node;
         }
+
         currentNode.end = true;
     }
 
@@ -80,13 +89,14 @@ public void insert(String word) {
     public boolean search(String word) {
         TrieNode currentNode = root;
         for (int i = 0; i < word.length(); i++) {
-            char ch = word.charAt(i);
-            TrieNode node = currentNode.child[ch - 'a'];
+            TrieNode node = currentNode.child.getOrDefault(word.charAt(i), null);
+
             if (node == null) {
                 return false;
             }
             currentNode = node;
         }
+
         return currentNode.end;
     }
 
@@ -104,40 +114,89 @@ public boolean search(String word) {
     public boolean delete(String word) {
         TrieNode currentNode = root;
         for (int i = 0; i < word.length(); i++) {
-            char ch = word.charAt(i);
-            TrieNode node = currentNode.child[ch - 'a'];
+            TrieNode node = currentNode.child.getOrDefault(word.charAt(i), null);
             if (node == null) {
                 return false;
             }
+
             currentNode = node;
         }
+
         if (currentNode.end) {
             currentNode.end = false;
             return true;
         }
+
         return false;
     }
 
     /**
-     * Helper method to print a string to the console.
+     * Counts the number of words in the trie
+     *<p>
+     * The method traverses the Trie and counts the number of words.
      *
-     * @param print The string to be printed.
+     * @return count of words
      */
-    public static void sop(String print) {
-        System.out.println(print);
+    public int countWords() {
+        return countWords(root);
+    }
+
+    private int countWords(TrieNode node) {
+        if (node == null) {
+            return 0;
+        }
+
+        int count = 0;
+        if (node.end) {
+            count++;
+        }
+
+        for (TrieNode child : node.child.values()) {
+            count += countWords(child);
+        }
+
+        return count;
     }
 
     /**
-     * Validates if a given word contains only lowercase alphabetic characters
-     * (a-z).
-     * <p>
-     * The method uses a regular expression to check if the word matches the pattern
-     * of only lowercase letters.
+     * Check if the prefix exists in the trie
      *
-     * @param word The word to be validated.
-     * @return true if the word is valid (only a-z), false otherwise.
+     * @param prefix the prefix to be checked in the Trie
+     * @return true / false depending on the prefix if exists in the Trie
      */
-    public static boolean isValid(String word) {
-        return word.matches("^[a-z]+$");
+    public boolean startsWithPrefix(String prefix) {
+        TrieNode currentNode = root;
+
+        for (int i = 0; i < prefix.length(); i++) {
+            TrieNode node = currentNode.child.getOrDefault(prefix.charAt(i), null);
+            if (node == null) {
+                return false;
+            }
+
+            currentNode = node;
+        }
+
+        return true;
+    }
+
+    /**
+     * Count the number of words starting with the given prefix in the trie
+     *
+     * @param prefix the prefix to be checked in the Trie
+     * @return count of words
+     */
+    public int countWordsWithPrefix(String prefix) {
+        TrieNode currentNode = root;
+
+        for (int i = 0; i < prefix.length(); i++) {
+            TrieNode node = currentNode.child.getOrDefault(prefix.charAt(i), null);
+            if (node == null) {
+                return 0;
+            }
+
+            currentNode = node;
+        }
+
+        return countWords(currentNode);
     }
 }