Incomplete solution for Leetcode Word Search

word-search.php

<?php
// https://leetcode.com/problems/word-search/

function exist($board, $word) {

    // count width
    $x = count($board[0]);

    // count height
    $y = 0;
    foreach($board as $ignored){
        ++$y;
    }

    // split & count word
    $split = str_split($word);
    $w = count($split) - 1;

    for($i=0; $i<$x-1; $i++) {
        for($j=0; $j <= $y; $j++) {
            for($k=0; $k<$w; $k++){
                if($split[$k] === $board[$i][$j]){
                    echo $split[$k] . '=' . $board[$i][$j] . ' located at xy: ' . $i . $j . '<br>';
                }
            }
        }
    }
}
$board = [
    ["A","B","C","E"],
    ["S","F","C","S"],
    ["A","D","E","E"]
];
$word = "ABCB";
exist($board, $word);