PHP implements common search and sorting algorithms

The following shares some of the most common algorithms and how to implement them in PHP.

1. Bubble sort

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

2. Merge sort

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

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

3. Binary search-recursive

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<$arr[$mid])
 return bin_search($arr, $low,$mid-1,$value);
 else
 return bin_search($arr,$mid+1,$high,$value);
 }
}

4. Binary search - non-recursive

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

5. Quick sort

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

6、选择排序

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

7、插入排序

function insertSort($arr) {
    $n=count($arr);
    for($i=1;$i<$n;$i++) {
        $tmp=$arr[$i];
        $j=$i-1;
        while($arr[$j]>$tmp) {
            $arr[$j+1]=$arr[$j];
            $arr[$j]=$tmp;
            $j--;
            if($j<0)
                break;
        }
    }
    return $arr;
}