PHP面试中常见的面试试题与算法例子

function reverse($str){
$r = array();
for($i=0; $i $r[] = mb_substr($str, $i, 1, 'UTF-8');
}
return implode(array_reverse($r));
}
echo reverse('www.111com.net天涯PHP博客');
//结果：'客博PHP涯天moc.ahphp.wwww'

function getext($url){
$data = parse_url($url);
$path = $data['path'];
$info = pathinfo($path);
return $info['extension'];
}
echo getext('https://www.111cn.net/ ');
//结果：'html'

function getrpath($path, $conpath){
$pathArr = explode('/', $path);
$conpathArr = explode('/', $conpath);
$dismatchlen = 0;
for($i=0; $i if($conpathArr[$i] != $pathArr[$i]){
$dismatchlen = count($pathArr) - $i;
$arrleft = array_slice($pathArr, $i);
break;
}
}
return str_repeat('../', $dismatchlen).implode('/', $arrleft);
}
$a = '/a/b/c/d/e.php';
$b = '/a/b/12/34/5.php';
echo getrpath($a, $b);
//结果：'../../../c/d/e.php'

function bubble_sort($arr) {
$n=count($arr);
for($i=0;$i for($j=$i+1;$j if($arr[$j] $temp=$arr[$i];
$arr[$i]=$arr[$j];
$arr[$j]=$temp;
}
}
}
return $arr;
}

function Merge(&$arr, $left, $mid, $right) {
$i = $left;
$j = $mid + 1;
$k = 0;
$temp = array();
while ($i {
if ($arr[$i] $temp[$k++] = $arr[$i++];
else
$temp[$k++] = $arr[$j++];
}
while ($i $temp[$k++] = $arr[$i++];
while ($j $temp[$k++] = $arr[$j++];
for ($i = $left, $j = 0; $i $arr[$i] = $temp[$j];
}

function MergeSort(&$arr, $left, $right)
{
if ($left {
$mid = floor(($left + $right) / 2);
MergeSort($arr, $left, $mid);
MergeSort($arr, $mid + 1, $right);
Merge($arr, $left, $mid, $right);
}
}

function bin_search($arr,$low,$high,$value) {
if($low>$high)
return false;
else {
$mid=floor(($low+$high)/2);
if($value==$arr[$mid])
return $mid;
elseif($value return bin_search($arr,$low,$mid-1,$value);
else
return bin_search($arr,$mid+1,$high,$value);
}
}

function quick_sort($arr) {
$n=count($arr);
if($n return $arr;
$key=$arr[0];
$left_arr=array();
$right_arr=array();
for($i=1;$i if($arr[$i] $left_arr[]=$arr[$i];
else
$right_arr[]=$arr[$i];
}
$left_arr=quick_sort($left_arr);
$right_arr=quick_sort($right_arr);
return array_merge($left_arr,array($key),$right_arr);
}

function select_sort($arr) {
$n=count($arr);
for($i=0;$i $k=$i;
for($j=$i+1;$j if($arr[$j] $k=$j;
}
if($k!=$i) {
$temp=$arr[$i];
$arr[$i]=$arr[$k];
$arr[$k]=$temp;
}
}
return $arr;
}

function insertSort($arr) {
$n=count($arr);
for($i=1;$i $tmp=$arr[$i];
$j=$i-1;
while($arr[$j]>$tmp) {
$arr[$j+1]=$arr[$j];
$arr[$j]=$tmp;
$j--;
if($j break;
}
}
return $arr;
}