剑指offer(PHP版改写)---矩阵中的路径

<?php
/**
 * Created by PhpStorm.
 * User: ftx
 * Date: 2019/7/24
 * Time: 11:18 AM
 */

//回溯法 找出矩阵中的路径

/**
 * @param $matrix  矩阵数组
 * @param $rows    行数
 * @param $cols    列数
 * @param $str     要寻找的字符串
 */
function hasPath($matrix,$rows,$cols,$str){
    if ($matrix==null||$rows<1||$cols<1||$str==null){
        return false;
    }

    $visited = [$rows*$cols];
    for($i = 0;$i<count($visited);++$i){
        $visited[$i]=0;
    }
    for ($row = 0;$row<$rows;++$row){
        for ($col=0;$col<$cols;++$col){
            if (hasPathCore($matrix,$rows,$cols,$row,$col,$str,$visited)){
                return true;
            }
        }
    }

    return 0;
}
//
function hasPathCore($matrix,$rows,$cols,$row,$col,$str,$visited)
{
    if (count($str) <= 0) {
        return true;
    }

    $hasPath = 0;
    $index = $row * $cols + $col;
//
    if ($row < 0 || $row >= $rows || $col < 0 || $col >= $cols || $matrix[$index] == false || $matrix[$index] != $str[0]) {
        return false;
    }
    $visited[$index] = true;
    $strRest = array_slice($str, 1);
    if (hasPathCore($matrix, $rows, $cols,  $row + 1, $col,$strRest, $visited) ||
        hasPathCore($matrix, $rows, $cols,  $row - 1, $col, $strRest,$visited) ||
        hasPathCore($matrix, $rows, $cols, $row, $col + 1,$strRest, $visited) ||
        hasPathCore($matrix, $rows, $cols, $row, $col - 1, $strRest,$visited)) {
        $hasPath = 1;
    } else {
        $visited[$index] = false;
    }

    return $hasPath;
}
$matrix = ['A','B','C','E','S','F','C','S','A','D','E','F'];
$str = ['A','B','C','D'];
print_r(hasPath($matrix,3,4,$str));