Common sorting algorithms in PHP

This article mainly introduces PHP in the common sorting algorithm, interested in the reference of friends, I hope to be helpful to everyone.

1. Bubble sort

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

2. Merge sort

//merge function merges and sorts the specified two ordered arrays (ARR1ARR2,)//We can find a third array, Then take the data from the beginning of the two arrays, whichever data is small, and then delete the data function Al_merge ($arrA, $arrB) {$arrC = Array (), which has just been taken, and then (count ($arrA) & & Count ($arrB)) {//Here constantly judge which value is small, will be small value to ARRC, but to the end must be left a few values,//is not left arra inside is the left ARRB inside and these several ordered values, Definitely bigger than all the values in ArrC, so use $arrc[] = $arrA [' 0 '] < $arrB [' 0 ']? Array_shift ($arrA): Array_shift ($arrB);} Return Array_merge ($arrC, $arrA, $arrB);} Merge sort main program function Al_merge_sort ($arr) {$len = count ($arr), if ($len <= 1) {return $arr;//recursive end condition, when this step is reached, the array has only one element left. That is, separate the array} $mid = Intval ($len/2); Take array middle $left_arr = Array_slice ($arr, 0, $mid); Split fraction Group 0-mid This section to the left Left_arr$right_arr = Array_slice ($arr, $mid); Split the fractional group mid-at the end of this section to the right Right_arr$left_arr = Al_merge_sort ($left _arr); After splitting the left, start the recursive merge to go up $right_arr = Al_merge_sort ($right _arr); The right split is finished and the recursion goes up $arr = Al_merge ($left _arr, $right _arr); Merge two arrays, continue recursive return $arr;} $arr = Array (5, 4, 7, 8, 3, 4, 2, 6, 4, 9);p Rint_r (Al_merge_sort ($arr)); 

3, binary search-recursion

Binary Lookup-recursive function Bin_search ($array, $low, $high, $k) {  if ($low <= $high) {    $mid = intval (($low + $high)/2);  } else{    return false;  }  if ($array [$mid] = = $k) {    return $mid;  } ElseIf ($k < $array [$mid]) {    return Bin_search ($array, $low, $mid-1, $k);  } else{    return Bin_search ($array, $mid +1, $high, $k);  }} $arr = Array (5, 4, 7, 3, 8, 4, 2, 6, 4, 9); $index = Bin_search ($arr, 0,10,12); The direct output is empty and does not understand Echo (Intval ($index));

4, two-part lookup-non-recursive

function Bin_search ($arr, $low, $high, $value) {//$arr array, $slow minimum index, $high maximum index $value lookup value while ($low <= $high) {   $mid =intval (($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. Select Sort

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. Insert Sort

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;}

Summary: The above is the entire content of this article, I hope to be able to help you learn.