adding TRIE data structure in PHP

Author: mirahman

DS/Tree/.DS_Store

@@ -0,0 +1,49 @@
+<?php
+
+/*
+ * Author: Mizanur Rahman <[email protected]>
+ * 
+ */
+
+namespace DS\Tree\Classes;
+
+use DS\Tree\Classes\TrieNode;
+
+class Trie
+{
+    public $root;
+    public function __construct()
+    {
+        $this->root = new TrieNode;
+    }
+
+    public function insert(string $key)
+    {
+        $key = strtolower($key);
+        $length = strlen($key);
+        $pCrawl = $this->root;
+        for ($level = 0; $level < $length; $level++) {
+            $index = ord($key[$level]) - ord('a');
+            if (is_null($pCrawl->children[$index]))
+                $pCrawl->children[$index] = new TrieNode();
+
+            $pCrawl = $pCrawl->children[$index];
+        }
+        $pCrawl->isEndOfWord = true;
+    }
+
+    public function search(string $key)
+    {
+        $key = strtolower($key);
+        $length = strlen($key);
+        $pCrawl = $this->root;
+        for ($level = 0; $level < $length; $level++) {
+            $index = ord($key[$level]) - ord('a');
+            if (is_null($pCrawl->children[$index]))
+                return false;
+
+            $pCrawl = $pCrawl->children[$index];
+        }
+        return (!is_null($pCrawl) && $pCrawl->isEndOfWord);
+    }
+}

DS/Tree/Classes/Trie.php

@@ -0,0 +1,21 @@
+<?php
+
+/*
+ * Author: Mizanur Rahman <[email protected]>
+ * 
+ */
+
+namespace DS\Tree\Classes;
+
+class TrieNode
+{
+    public $children;
+    public $isEndOfWord;
+    const ALPHABETSIZE = 26;
+    
+    public function __construct()
+    {
+        $this->isEndOfWord = false;
+        $this->children = array_fill(0,self::ALPHABETSIZE, null);
+    }
+}

DS/Tree/Classes/TrieNode.php

@@ -0,0 +1,30 @@
+<?php
+
+/*
+ * Author: Mizanur Rahman <[email protected]>
+ * 
+ */
+
+include __DIR__ . '/../../../Vendor/Autoload.php';
+
+use \DS\Tree\Classes\Trie;
+
+try {
+    $keys = ["dhaka", "bangladesh", "there", "answer", "any", "by", "bye", "their"];
+
+    $trie = new Trie();
+    // Construct trie 
+    for ($i = 0; $i < count($keys); $i++)
+        $trie->insert($keys[$i]);
+
+    $searches = ["dhaka", "three", "these", "there", "the", "any", "DHAKA", "anyone", "desh"];
+    foreach ($searches as $search) {
+        if ($trie->search($search)) {
+            echo "$search - is present in the trie \n";
+        } else {
+            echo "$search - is not present in the trie \n";
+        }
+    }
+} catch (Exception $e) {
+    echo $e->getMessage();
+}