php实现最大自序和算法

$arr =  [-2,1,-3,4,-1,2,1,-5,4];

   function maxSubArray($nums) {
        for($i=1;$i<count($nums);$i++)
            $nums[$i] = max($nums[$i],$nums[$i]+$nums[$i-1]);
        return max($nums);
    }

echo maxSubArray($a);

$arr =  [-2,1,-3,4,-1,2,1,-5,4];
$len = count($arr);
$b =[];
$b[0] = $arr[0];
$max = $arr[0] >0 ?$arr[0]:0;
$start_x = 0;
for($i=1;$i<$len;$i++)
{
    if(($b[$i-1] + $arr[$i]) > $arr[$i]){
        $b[$i] = $b[$i-1] + $arr[$i];
    }else{
        $b[$i] = $arr[$i];
        $start_x = $i; ;
    }    
    if($max < $b[$i]) {    
        $max = $b[$i];    
        $end_x = $i;
    }
}
print ‘最大子和: ‘.$max."\n";
print ‘开始位置: ‘.$start_x."\t";
print ‘结束位置: ‘.$end_x."\n";
print ‘最大子序列:‘;
for($i=$start_x;$i<=$end_x;$i++){
    print $arr[$i].‘ ‘;
}