Improving summing algorithm for 2048 game developed with PHP - php

Question

I challenged myself to improve my skills by doing some individual projects and for now I am stuck with the 2048.
I have the text file which stores the present values of the game.
128 64 32 16 32 8 8 8 16 4 4 4 8 2 2 2
<?php
$logs = file("logs-2048.txt");
if ($_SERVER["REQUEST_METHOD"] == "POST") {
file_put_contents('logs-2048.txt', '');
$tableValues = [];
$arrayLine = explode(" ", $logs[0]);
for($g=0; $g<4; $g++) {
$newLine = [];
for($h=0; $h<4; $h++) {
array_push($newLine, htmlspecialchars($arrayLine[$g*4+$h]));
}
array_push($tableValues, $newLine);
}
$direction = $_POST["action-joueur"];
$string = "";
if($direction == "^") {
for($g = 0; $g < 3; $g++) {
for ($h = 0; $h < 4; $h++) {
for ($i = 0; $i < 3; $i++) {
if ($tableValues[$i][$h] == $tableValues[$i+1][$h] || $tableValues[$i][$h] == 0) {
$tableValues[$i][$h] += $tableValues[$i+1][$h];
$tableValues[$i+1][$h] = 0;
}
}
}
}
} else if ($direction == "v") {
//Almost simillar stuff as for ^
} else if ($direction == "<") {
//Almost similar stuff as for ^
} else if ($direction == ">") {
//Almost similar stuff as for ^
}
$arrayEmpty = [];
for($g = 0; $g < 4; $g++) {
for($h = 0; $h < 4; $h++) {
if($tableValues[$g][$h] == 0) {
array_push($arrayEmpty, [$g, $h]);
}
}
}
$findRand = mt_rand(0, count($arrayEmpty)-1);
$tableValues[$arrayEmpty[$findRand][0]][$arrayEmpty[$findRand][1]] = 2;
for($g = 0; $g < 4; $g++) {
for ($h = 0; $h < 4; $h++) {
$string = $string.$tableValues[$g][$h]." ";
}
}
file_put_contents("logs-2048.txt", $string);
}
?>
The first loop is to parse the array that I take from the file, and convert it to a 2 dimensional array(table).
The problem is in the next 4 nested loops which does the summing, I can't figure how can I do other way then just use another loop(first one for each nested loop) which goes 3 times back if some numbers were stuck somewhere adding themselves (EX. 2 2 2 2 in first column => 4 2 2 0 => 4 4 0 0 => 8 0 0 0).
I am 100% sure that the algorithms for summing is terribly inefficient, but I can't figure out what solution I can provide to make it faster and more intuitive, then have 4 for's... I tried also to look at different resources on internet but it's pretty messed up for me because I am starting with php.
Yes, I know that php isn't the best way to do, I'll do myself with
Javascript, but I need it for learning, any ideas or tips to improve the algorithm will be greatly appreciated.