Find the longest word given a dictionary - php

Question

I'm reading overflow for years but never had to post anything (thanks to great answers) until now because i can't rly find solution for my problem.
I'm kinda new to PHP.
So I'm creating game where you have to find a longest word with 12 random generated letters. I actually did this successfully in C# and Java, but now I'm porting some of code to PHP because i'm working on multiplayer version and some stuff will be on server.
So i did all this using this great thread (Answer by Thomas Jungblut):
Find the longest word given a collection
Now i tried to do same in PHP but, it's weird for me. I get some crazy result's and i dont know how to replicate this java method in php:
arraycopy(Object src, int srcPos, Object dest, int destPos, int length)
I'm not getting any error, but obvisuly thing is not working, is there anyone that can maybe help me to work this out?
UPDATE: BTW, i know post might be confusing im new to posting here...so forgive me ^^
I "fixed" code, it will now find me longest word. But there is bug somewhere. Bug is allowing algortithm to use one character more than once, which should not be possible.
I think problem is here:
$newDict[$index] = array_splice($allowedCharacters, $index +1, count($allowedCharacters) - ($index +1));
This is my Current Code:
parse_dictionary.php
<?php
$ouput = array();
$mysqli = new mysqli('localhost','root','','multiquiz_db');
$mysqli->set_charset('utf8');
if ($result = $mysqli->query("SELECT word FROM words_live")) {
while($row = $result->fetch_array(MYSQL_ASSOC)) {
//echo(mb_convert_encoding($row['word'], 'HTML-ENTITIES', 'utf-8'));
array_push($ouput, $row['word']);
}
//echo utf8_decode(json_encode($ouput));
}
$result->close();
$mysqli->close();
?>
Trie.php
<?php
class Trie
{
public $children = array();
public $value = null;
public $word = null;
public function __construct($value = null)
{
$this->value = $value;
}
public function adda($array)
{
$this->addb($array, 0);
}
public function addb($array, $offset)
{
foreach ($this->children as $child)
{
if($child->value == $array[$offset])
{
$child->addb($array, $offset + 1);
return;
}
}
$trieNode = new Trie($array[$offset]);
array_push($this->children, $trieNode);
if($offset < count($array) - 1)
{
$trieNode->addb($array, $offset+1);
}
else
{
$trieNode->word = implode(" ", $array);
}
}
}
?>
Index.php
<?php
include 'Trie.php';
include 'parse_dictionary.php';
ini_set('memory_limit', '1024M'); // or you could use 1G
header('Content-Type: text/html; charset=utf-8');
mb_internal_encoding("UTF-8");
class LongestWord
{
public $root = null;
public function __construct($ouput)
{
$this->root = new Trie();
foreach ($ouput as $word)
{
//echo($word);
//echo(str_split_unicode($word)[0]);
$this->root->adda(str_split_unicode($word));
}
}
public function search($cs)
{
return $this->visit($this->root, $cs);
}
function visit($n, $allowedCharacters)
{
$bestMatch = null;
if(count($n->children) == 0)
{
$bestMatch = $n->word;
}
foreach($n->children as $child)
{
if($this->contains($allowedCharacters, $child->value))
{
$result = $this->visit($child, $this->remove($allowedCharacters, $child->value));
if($bestMatch == null || $result != null && strlen($bestMatch) < strlen($result))
{
$bestMatch = $result;
}
}
}
return $bestMatch;
}
function remove($allowedCharacters, $value)
{
$newDict = $allowedCharacters;
if(($key = array_search($value, $newDict)))
{
unset($newDict[$key]);
}
return $newDict;
}
function contains($allowedCharacters, $value)
{
foreach($allowedCharacters as $x)
{
if($value == $x)
{
// echo $value . "=====". $x. "|||||||";
return true;
}
else
{
//echo $value . "!!===". $x. "|||||||";
}
}
return false;
}
}
function str_split_unicode($str, $l = 0) {
if ($l > 0) {
$ret = array();
$len = mb_strlen($str, "UTF-8");
for ($i = 0; $i < $len; $i += $l) {
$ret[] = mb_substr($str, $i, $l, "UTF-8");
}
return $ret;
}
return preg_split("//u", $str, -1, PREG_SPLIT_NO_EMPTY);
}
$chars = 'IIOIOFNČGDĆJ';
$testCharacters = str_split_unicode($chars);
$lw = new LongestWord($ouput);
echo($lw->search($testCharacters));
?>

Answer 1

As you're using MySQL, here's an approach that will let the DB server do the work.
It's a bit dirty, because you have to add several WHERE conditions with regex matching, which will have a rather poor performance. (Unfortunately, I could not come up with a regex that would require all of the letters in one expression, but I'd be happy to be corrected.)
However, I have tested it on a database table of >200000 entries; it delivers results within less than 0.3 sec.
SELECT word
FROM words_live
WHERE
word REGEXP "a" AND
word REGEXP "b" AND
word REGEXP "c" AND
word REGEXP "d"
ORDER BY LENGTH(word) DESC
LIMIT 1;
Obviously, you must generate one word REGEXP "a" condition per letter in your PHP code when constructing the query.
The query should then give you exactly one result, namely the longest word in the database containing all of the characters.

Answer 2

I solved problem with this function, full working code updated in question post
function remove($allowedCharacters, $value)
{
$newDict = $allowedCharacters;
if(($key = array_search($value, $newDict)))
{
unset($newDict[$key]);
}
return $newDict;
}
removed old one:
function remove($allowedCharacters, $value)
{
$newDict = [count($allowedCharacters) - 1];
$index = 0;
foreach($allowedCharacters as $x)
{
if($x != $value)
{
$newDict[$index++] = $x;
}
else
{
//we removed the first hit, now copy the rest
break;
}
}
//System.arraycopy(allowedCharacters, index + 1, newDict, index, allowedCharacters.length - (index + 1)); JAVA arraycopy(Object src, int srcPos, Object dest, int destPos, int length)
//$newDict[$index] = array_splice($allowedCharacters, $index +1, count($allowedCharacters) - ($index +1));
//$newDict = $allowedCharacters;
return $newDict;
}