Enhanced Trie Data Structure with Case-Insensitive Feature and additional Test Cases

DataStructures/Trie/Trie.php

@@ -1,8 +1,9 @@
 <?php
 
 /*
- * Created by: Ramy-Badr-Ahmed (https://github.com/Ramy-Badr-Ahmed) in Pull Request: #162
+ * Created by: Ramy-Badr-Ahmed (https://github.com/Ramy-Badr-Ahmed) in Pull Request #162 and #172
  * https://github.com/TheAlgorithms/PHP/pull/162
+ * https://github.com/TheAlgorithms/PHP/pull/172
  *
  * Please mention me (@Ramy-Badr-Ahmed) in any issue or pull request addressing bugs/corrections to this file.
  * Thank you!
@@ -61,6 +62,7 @@ public function search(string $word): bool
      */
     public function startsWith(string $prefix): array
     {
+        $prefix = strtolower($prefix);  // Normalize the prefix to lowercase
         $node = $this->root;
         for ($i = 0; $i < strlen($prefix); $i++) {
             $char = $prefix[$i];

DataStructures/Trie/TrieNode.php

@@ -1,8 +1,9 @@
 <?php
 
 /*
- * Created by: Ramy-Badr-Ahmed (https://github.com/Ramy-Badr-Ahmed) in Pull Request: #162
+ * Created by: Ramy-Badr-Ahmed (https://github.com/Ramy-Badr-Ahmed) in Pull Request #162 and #172
  * https://github.com/TheAlgorithms/PHP/pull/162
+ * https://github.com/TheAlgorithms/PHP/pull/172
  *
  * Please mention me (@Ramy-Badr-Ahmed) in any issue or pull request addressing bugs/corrections to this file.
  * Thank you!
@@ -27,6 +28,7 @@ public function __construct()
      */
     public function addChild(string $char): TrieNode
     {
+        $char = $this->normalizeChar($char);
         if (!isset($this->children[$char])) {
             $this->children[$char] = new TrieNode();
         }
@@ -38,6 +40,7 @@ public function addChild(string $char): TrieNode
      */
     public function hasChild(string $char): bool
     {
+        $char = $this->normalizeChar($char);
         return isset($this->children[$char]);
     }
 
@@ -46,6 +49,15 @@ public function hasChild(string $char): bool
      */
     public function getChild(string $char): ?TrieNode
     {
+        $char = $this->normalizeChar($char);
         return $this->children[$char] ?? null;
     }
+
+    /**
+     * Normalize the character to lowercase.
+     */
+    private function normalizeChar(string $char): string
+    {
+        return strtolower($char);
+    }
 }

tests/DataStructures/TrieTest.php

@@ -1,8 +1,9 @@
 <?php
 
 /*
- * Created by: Ramy-Badr-Ahmed (https://github.com/Ramy-Badr-Ahmed) in Pull Request: #162
+ * Created by: Ramy-Badr-Ahmed (https://github.com/Ramy-Badr-Ahmed) in Pull Request #162 and #172
  * https://github.com/TheAlgorithms/PHP/pull/162
+ * https://github.com/TheAlgorithms/PHP/pull/172
  *
  * Please mention me (@Ramy-Badr-Ahmed) in any issue or pull request addressing bugs/corrections to this file.
  * Thank you!
@@ -14,6 +15,7 @@
 require_once __DIR__ . '/../../DataStructures/Trie/TrieNode.php';
 
 use DataStructures\Trie\Trie;
+use DataStructures\Trie\TrieNode;
 use PHPUnit\Framework\TestCase;
 
 class TrieTest extends TestCase
@@ -25,6 +27,9 @@ protected function setUp(): void
         $this->trie = new Trie();
     }
 
+    /**
+     * Test insertion and search functionality of the Trie.
+    */
     public function testInsertAndSearch()
     {
         $this->trie->insert('the');
@@ -42,6 +47,48 @@ public function testInsertAndSearch()
         );
     }
 
+    /**
+     * Test insertion and search functionality with mixed case words.
+     */
+    public function testInsertAndSearchMixedCase()
+    {
+        $this->trie->insert('Apple');
+        $this->trie->insert('aPPle');
+        $this->assertTrue($this->trie->search('apple'), 'Expected "apple" to be found in the Trie.');
+        $this->assertTrue($this->trie->search('APPLE'), 'Expected "APPLE" to be found in the Trie.');
+    }
+
+    /**
+     * Test insertion and search functionality with special characters.
+     */
+    public function testInsertAndSearchWithSpecialCharacters()
+    {
+        $this->trie->insert('hello123');
+        $this->trie->insert('[email protected]');
+        $this->assertTrue($this->trie->search('hello123'), 'Expected "hello123" to be found in the Trie.');
+        $this->assertTrue(
+            $this->trie->search('[email protected]'),
+            'Expected "[email protected]" to be found in the Trie.'
+        );
+        $this->assertTrue(
+            $this->trie->search('HELLO123'),
+            'Expected "HELLO123" not to be found in the Trie (case-sensitive).'
+        );
+    }
+
+    /**
+     * Test insertion and search functionality with long strings.
+     */
+    public function testInsertAndSearchLongStrings()
+    {
+        $longString = str_repeat('a', 1000);
+        $this->trie->insert($longString);
+        $this->assertTrue($this->trie->search($longString), 'Expected the long string to be found in the Trie.');
+    }
+
+    /**
+     * Test the startsWith functionality of the Trie.
+     */
     public function testStartsWith()
     {
         $this->trie->insert('hello');
@@ -58,9 +105,31 @@ public function testStartsWith()
         );
     }
 
+    /**
+     * Test startsWith functionality with mixed case prefixes.
+     */
+    public function testStartsWithMixedCase()
+    {
+        $this->trie->insert('PrefixMatch');
+        $this->trie->insert('PreFixTesting');
+        $this->assertEquals(
+            ['prefixmatch', 'prefixtesting'],
+            $this->trie->startsWith('prefix'),
+            'Expected words starting with "prefix" to be found in the Trie (case-insensitive).'
+        );
+
+        $this->assertEquals(
+            ['prefixmatch', 'prefixtesting'],
+            $this->trie->startsWith('PREFIX'),
+            'Expected words starting with "PREFIX" to be found in the Trie (case-insensitive).'
+        );
+    }
+
+    /**
+     * Test deletion of existing words from the Trie.
+     */
     public function testDelete()
     {
-        // Insert words into the Trie
         $this->trie->insert('the');
         $this->trie->insert('universe');
         $this->trie->insert('is');
@@ -80,12 +149,51 @@ public function testDelete()
         $this->assertTrue($this->trie->search('rather'), 'Expected "rather" to be found.');
     }
 
+    /**
+     * Test deletion of mixed case words from the Trie.
+     */
+    public function testDeleteMixedCase()
+    {
+        $this->trie->insert('MixedCase');
+        $this->assertTrue($this->trie->search('mixedcase'), 'Expected "mixedcase" to be found before deletion.');
+
+        $this->trie->delete('MIXEDCASE');
+        $this->assertFalse(
+            $this->trie->search('MixedCase'),
+            'Expected "MixedCase" not to be found after deletion (case-insensitive).'
+        );
+    }
+
+    /**
+     * Test deletion of words with special characters.
+     */
+    public function testDeleteWithSpecialCharacters()
+    {
+        $this->trie->insert('spec!@l#chars');
+        $this->assertTrue(
+            $this->trie->search('spec!@l#chars'),
+            'Expected "spec!@l#chars" to be found before deletion.'
+        );
+
+        $this->trie->delete('SPEC!@L#CHARS');
+        $this->assertFalse(
+            $this->trie->search('spec!@l#chars'),
+            'Expected "spec!@l#chars" not to be found after deletion.'
+        );
+    }
+
+    /**
+     * Test deletion of a non-existent word from the Trie.
+     */
     public function testDeleteNonExistentWord()
     {
         $this->trie->delete('nonexistent');
         $this->assertFalse($this->trie->search('nonexistent'), 'Expected "nonexistent" to not be found.');
     }
 
+    /**
+     * Test traversal of the Trie and retrieval of words.
+     */
     public function testTraverseTrieNode()
     {
         $this->trie->insert('hello');
@@ -99,11 +207,17 @@ public function testTraverseTrieNode()
         $this->assertCount(3, $words, 'Expected 3 words in the Trie.');
     }
 
+    /**
+     * Test behavior of an empty Trie.
+     */
     public function testEmptyTrie()
     {
         $this->assertEquals([], $this->trie->getWords(), 'Expected an empty Trie to return an empty array.');
     }
 
+    /**
+     * Test retrieval of words from the Trie.
+     */
     public function testGetWords()
     {
         $this->trie->insert('apple');
@@ -117,19 +231,28 @@ public function testGetWords()
         $this->assertCount(3, $words, 'Expected 3 words in the Trie.');
     }
 
+    /**
+     * Test insertion of an empty string into the Trie.
+     */
     public function testInsertEmptyString()
     {
         $this->trie->insert('');
         $this->assertTrue($this->trie->search(''), 'Expected empty string to be found in the Trie.');
     }
 
+    /**
+     * Test deletion of an empty string from the Trie.
+     */
     public function testDeleteEmptyString()
     {
         $this->trie->insert('');
         $this->trie->delete('');
         $this->assertFalse($this->trie->search(''), 'Expected empty string not to be found after deletion.');
     }
 
+    /**
+     * Test the startsWith functionality with a common prefix.
+     */
     public function testStartsWithWithCommonPrefix()
     {
         $this->trie->insert('trie');
@@ -142,4 +265,38 @@ public function testStartsWithWithCommonPrefix()
         $this->assertContains('trier', $words, 'Expected "trier" to be found with prefix "tri".');
         $this->assertCount(3, $words, 'Expected 3 words with prefix "tri".');
     }
+
+    /**
+     * Test retrieval of the root node of the Trie.
+     */
+    public function testGetRoot()
+    {
+        $root = $this->trie->getRoot();
+        $this->assertInstanceOf(TrieNode::class, $root, 'Expected root to be an instance of TrieNode.');
+        $this->assertFalse($root->isEndOfWord, 'Expected the root node not to be the end of a word.');
+        $this->assertCount(0, $root->children, 'Expected the root node to have no children initially.');
+    }
+
+    /**
+     * Test retrieval of the root node after populating the Trie with words.
+     */
+    public function testGetRootAfterPopulation()
+    {
+        $this->trie->insert('TheAlgorithms');
+        $this->trie->insert('PHP');
+        $this->trie->insert('DSA');
+
+        $root = $this->trie->getRoot();
+
+        $this->assertInstanceOf(TrieNode::class, $root, 'Expected root to be an instance of TrieNode.');
+
+        // Assert that the root node is not marked as the end of a word
+        $this->assertFalse($root->isEndOfWord, 'Expected the root node not to be the end of a word.');
+
+        // Assert that the root node has children corresponding to the inserted words
+        $this->assertCount(3, $root->children, 'Expected the root node to have 3 children after inserting words.');
+        $this->assertTrue($root->hasChild('t'), 'Expected root to have a child for "t".');
+        $this->assertTrue($root->hasChild('p'), 'Expected root to have a child for "p".');
+        $this->assertTrue($root->hasChild('D'), 'Expected root to have a child for "D".');
+    }
 }