Improve TrieImp.java comments & enhance readability (#5526)

DIRECTORY.md

@@ -22,7 +22,7 @@
             * [WordSearch](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/backtracking/WordSearch.java)
           * bitmanipulation
             * [BitSwap](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/BitSwap.java)
-            * [CountSetBits](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/CountSetBits.java)
+            * [CountSetBits](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/CountSetBits.java)
             * [HighestSetBit](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/HighestSetBit.java)
             * [IndexOfRightMostSetBit](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/IndexOfRightMostSetBit.java)
             * [IsEven](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/bitmanipulation/IsEven.java)
@@ -69,7 +69,7 @@
             * [HexaDecimalToBinary](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/conversions/HexaDecimalToBinary.java)
             * [HexaDecimalToDecimal](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/conversions/HexaDecimalToDecimal.java)
             * [HexToOct](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/conversions/HexToOct.java)
-            * [IntegerToEnglish] (https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/conversions/IntegerToEnglish.java)
+            * [IntegerToEnglish](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/conversions/IntegerToEnglish.java)
             * [IntegerToRoman](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/conversions/IntegerToRoman.java)
             * [OctalToBinary](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/conversions/OctalToBinary.java)
             * [OctalToDecimal](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/conversions/OctalToDecimal.java)
@@ -410,7 +410,7 @@
             * [WordBoggle](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/misc/WordBoggle.java)
           * others
             * [ArrayLeftRotation](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/ArrayLeftRotation.java)
-            * [ArrayRightRotation](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/others/ArrayRightRotation.java)
+            * [ArrayRightRotation](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/ArrayRightRotation.java)
             * [BankersAlgorithm](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/BankersAlgorithm.java)
             * [BFPRT](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/BFPRT.java)
             * [BoyerMoore](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/BoyerMoore.java)
@@ -559,8 +559,8 @@
             * [CharactersSame](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/CharactersSame.java)
             * [CheckAnagrams](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/CheckAnagrams.java)
             * [CheckVowels](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/CheckVowels.java)
-            * [CountChar](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/CountChar.java)
+            * [CountChar](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/CountChar.java)
-            * [CountWords](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/CountWords.java)
+            * [CountWords](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/CountWords.java)
             * [HammingDistance](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/HammingDistance.java)
             * [HorspoolSearch](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/HorspoolSearch.java)
             * [Isomorphic](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/Isomorphic.java)
@@ -575,13 +575,13 @@
             * [Pangram](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/Pangram.java)
             * [PermuteString](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/PermuteString.java)
             * [RabinKarp](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/RabinKarp.java)
-            * [ReturnSubsequence](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/ReturnSubsequence.java)
+            * [ReturnSubsequence](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/ReturnSubsequence.java)
             * [ReverseString](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/ReverseString.java)
             * [ReverseStringRecursive](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/ReverseStringRecursive.java)
             * [ReverseWordsInString](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/ReverseWordsInString.java)
             * [Rotation](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/Rotation.java)
             * [StringCompression](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/StringCompression.java)
-            * [StringMatchFiniteAutomata](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/others/StringMatchFiniteAutomata.java)
+            * [StringMatchFiniteAutomata](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/StringMatchFiniteAutomata.java)
             * [Upper](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/Upper.java)
             * [ValidParentheses](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/ValidParentheses.java)
             * [WordLadder](https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/strings/WordLadder.java)
@@ -606,7 +606,7 @@
             * [WordSearchTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/backtracking/WordSearchTest.java)
           * bitmanipulation
             * [BitSwapTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/bitmanipulation/BitSwapTest.java)
-            * [CountSetBitsTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/others/CountSetBitsTest.java)
+            * [CountSetBitsTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/bitmanipulation/CountSetBitsTest.java)
             * [HighestSetBitTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/bitmanipulation/HighestSetBitTest.java)
             * [IndexOfRightMostSetBitTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/bitmanipulation/IndexOfRightMostSetBitTest.java)
             * [IsEvenTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/bitmanipulation/IsEvenTest.java)
@@ -621,6 +621,7 @@
             * [BlowfishTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/ciphers/BlowfishTest.java)
             * [CaesarTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/ciphers/CaesarTest.java)
             * [DESTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/ciphers/DESTest.java)
+            * [HillCipherTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/ciphers/HillCipherTest.java)
             * [PlayfairTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/ciphers/PlayfairTest.java)
             * [PolybiusTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/ciphers/PolybiusTest.java)
             * [RSATest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/ciphers/RSATest.java)
@@ -639,6 +640,7 @@
             * [HexaDecimalToBinaryTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/conversions/HexaDecimalToBinaryTest.java)
             * [HexaDecimalToDecimalTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/conversions/HexaDecimalToDecimalTest.java)
             * [HexToOctTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/conversions/HexToOctTest.java)
+            * [IntegerToEnglishTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/conversions/IntegerToEnglishTest.java)
             * [IntegerToRomanTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/conversions/IntegerToRomanTest.java)
             * [OctalToBinaryTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/conversions/OctalToBinaryTest.java)
             * [OctalToDecimalTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/conversions/OctalToDecimalTest.java)
@@ -727,6 +729,7 @@
               * [SameTreesCheckTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/SameTreesCheckTest.java)
               * [SplayTreeTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/datastructures/trees/SplayTreeTest.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)
               * [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
@@ -991,8 +994,8 @@
             * [CharacterSameTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/CharacterSameTest.java)
             * [CheckAnagramsTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/CheckAnagramsTest.java)
             * [CheckVowelsTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/CheckVowelsTest.java)
-            * [CountCharTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/others/CountCharTest.java)
+            * [CountCharTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/CountCharTest.java)
-            * [CountWordsTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/others/CountWordsTest.java)
+            * [CountWordsTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/CountWordsTest.java)
             * [HammingDistanceTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/HammingDistanceTest.java)
             * [HorspoolSearchTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/HorspoolSearchTest.java)
             * [IsomorphicTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/IsomorphicTest.java)
@@ -1005,13 +1008,13 @@
             * [PalindromeTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/PalindromeTest.java)
             * [PangramTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/PangramTest.java)
             * [PermuteStringTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/PermuteStringTest.java)
-            * [ReturnSubsequenceTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/others/ReturnSubsequenceTest.java)
+            * [ReturnSubsequenceTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/ReturnSubsequenceTest.java)
             * [ReverseStringRecursiveTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/ReverseStringRecursiveTest.java)
             * [ReverseStringTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/ReverseStringTest.java)
             * [ReverseWordsInStringTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/ReverseWordsInStringTest.java)
             * [RotationTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/RotationTest.java)
             * [StringCompressionTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/StringCompressionTest.java)
-            * [StringMatchFiniteAutomataTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/others/StringMatchFiniteAutomataTest.java)
+            * [StringMatchFiniteAutomataTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/StringMatchFiniteAutomataTest.java)
             * [UpperTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/UpperTest.java)
             * [ValidParenthesesTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/ValidParenthesesTest.java)
             * [WordLadderTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/strings/WordLadderTest.java)

src/main/java/com/thealgorithms/datastructures/trees/TrieImp.java

@@ -1,19 +1,35 @@
 package com.thealgorithms.datastructures.trees;
 
-import java.util.Scanner;
-
 /**
- * Trie Data structure implementation without any libraries
+ * Trie Data structure implementation without any libraries.
+ * <p>
+ * The Trie (also known as a prefix tree) is a special tree-like data structure
+ * that is used to store a dynamic set or associative array where the keys are
+ * usually strings. It is highly efficient for prefix-based searches.
+ * <p>
+ * This implementation supports basic Trie operations like insertion, search,
+ * and deletion.
+ * <p>
+ * Each node of the Trie represents a character and has child nodes for each
+ * possible character.
  *
  * @author <a href="https://github.com/dheeraj92">Dheeraj Kumar Barnwal</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;
@@ -22,10 +38,22 @@ public class TrieImp {
 
     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();
     }
 
+    /**
+     * Inserts a word into the Trie.
+     * <p>
+     * The method traverses the Trie from the root, character by character, and adds
+     * nodes if necessary. It marks the last node of the word as an end node.
+     *
+     * @param word The word to be inserted into the Trie.
+     */
     public void insert(String word) {
         TrieNode currentNode = root;
         for (int i = 0; i < word.length(); i++) {
@@ -39,6 +67,16 @@ public class TrieImp {
         currentNode.end = true;
     }
 
+    /**
+     * Searches for a word in the Trie.
+     * <p>
+     * This method traverses the Trie based on the input word and checks whether
+     * the word exists. It returns true if the word is found and its end flag is
+     * true.
+     *
+     * @param word The word to search in the Trie.
+     * @return true if the word exists in the Trie, false otherwise.
+     */
     public boolean search(String word) {
         TrieNode currentNode = root;
         for (int i = 0; i < word.length(); i++) {
@@ -52,6 +90,17 @@ public class TrieImp {
         return currentNode.end;
     }
 
+    /**
+     * Deletes a word from the Trie.
+     * <p>
+     * The method traverses the Trie to find the word and marks its end flag as
+     * false.
+     * It returns true if the word was successfully deleted, false if the word
+     * wasn't found.
+     *
+     * @param word The word to be deleted from the Trie.
+     * @return true if the word was found and deleted, false if it was not found.
+     */
     public boolean delete(String word) {
         TrieNode currentNode = root;
         for (int i = 0; i < word.length(); i++) {
@@ -69,75 +118,26 @@ public class TrieImp {
         return false;
     }
 
+    /**
+     * Helper method to print a string to the console.
+     *
+     * @param print The string to be printed.
+     */
     public static void sop(String print) {
         System.out.println(print);
     }
 
     /**
-     * Regex to check if word contains only a-z character
+     * 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.
+     *
+     * @param word The word to be validated.
+     * @return true if the word is valid (only a-z), false otherwise.
      */
     public static boolean isValid(String word) {
         return word.matches("^[a-z]+$");
     }
-
-    public static void main(String[] args) {
-        TrieImp obj = new TrieImp();
-        String word;
-        @SuppressWarnings("resource") Scanner scan = new Scanner(System.in);
-        sop("string should contain only a-z character for all operation");
-        while (true) {
-            sop("1. Insert\n2. Search\n3. Delete\n4. Quit");
-            try {
-                int t = scan.nextInt();
-                switch (t) {
-                case 1:
-                    word = scan.next();
-                    if (isValid(word)) {
-                        obj.insert(word);
-                    } else {
-                        sop("Invalid string: allowed only a-z");
-                    }
-                    break;
-                case 2:
-                    word = scan.next();
-                    boolean resS = false;
-                    if (isValid(word)) {
-                        resS = obj.search(word);
-                    } else {
-                        sop("Invalid string: allowed only a-z");
-                    }
-                    if (resS) {
-                        sop("word found");
-                    } else {
-                        sop("word not found");
-                    }
-                    break;
-                case 3:
-                    word = scan.next();
-                    boolean resD = false;
-                    if (isValid(word)) {
-                        resD = obj.delete(word);
-                    } else {
-                        sop("Invalid string: allowed only a-z");
-                    }
-                    if (resD) {
-                        sop("word got deleted successfully");
-                    } else {
-                        sop("word not found");
-                    }
-                    break;
-                case 4:
-                    sop("Quit successfully");
-                    System.exit(1);
-                    break;
-                default:
-                    sop("Input int from 1-4");
-                    break;
-                }
-            } catch (Exception e) {
-                String badInput = scan.next();
-                sop("This is bad input: " + badInput);
-            }
-        }
-    }
 }

src/test/java/com/thealgorithms/datastructures/trees/TrieImpTest.java

@@ -0,0 +1,76 @@
+package com.thealgorithms.datastructures.trees;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class TrieImpTest {
+    private TrieImp trie;
+
+    @BeforeEach
+    public void setUp() {
+        trie = new TrieImp();
+    }
+
+    @Test
+    public void testInsertAndSearchBasic() {
+        String word = "hello";
+        trie.insert(word);
+        assertTrue(trie.search(word), "Search should return true for an inserted word.");
+    }
+
+    @Test
+    public void testSearchNonExistentWord() {
+        String word = "world";
+        assertFalse(trie.search(word), "Search should return false for a non-existent word.");
+    }
+
+    @Test
+    public void testInsertAndSearchMultipleWords() {
+        String word1 = "cat";
+        String word2 = "car";
+        trie.insert(word1);
+        trie.insert(word2);
+
+        assertTrue(trie.search(word1), "Search should return true for an inserted word.");
+        assertTrue(trie.search(word2), "Search should return true for another inserted word.");
+        assertFalse(trie.search("dog"), "Search should return false for a word not in the Trie.");
+    }
+
+    @Test
+    public void testDeleteExistingWord() {
+        String word = "remove";
+        trie.insert(word);
+        assertTrue(trie.delete(word), "Delete should return true for an existing word.");
+        assertFalse(trie.search(word), "Search should return false after deletion.");
+    }
+
+    @Test
+    public void testDeleteNonExistentWord() {
+        String word = "nonexistent";
+        assertFalse(trie.delete(word), "Delete should return false for a non-existent word.");
+    }
+
+    @Test
+    public void testInsertAndSearchPrefix() {
+        String prefix = "pre";
+        String word = "prefix";
+        trie.insert(prefix);
+        trie.insert(word);
+
+        assertTrue(trie.search(prefix), "Search should return true for an inserted prefix.");
+        assertTrue(trie.search(word), "Search should return true for a word with the prefix.");
+        assertFalse(trie.search("pref"), "Search should return false for a prefix that is not a full word.");
+    }
+
+    @Test
+    public void testIsValidWord() {
+        assertTrue(TrieImp.isValid("validword"), "Word should be valid (only lowercase letters).");
+        assertFalse(TrieImp.isValid("InvalidWord"), "Word should be invalid (contains uppercase letters).");
+        assertFalse(TrieImp.isValid("123abc"), "Word should be invalid (contains numbers).");
+        assertFalse(TrieImp.isValid("hello!"), "Word should be invalid (contains special characters).");
+        assertFalse(TrieImp.isValid(""), "Empty string should be invalid.");
+    }
+}