PHP four basic algorithms: bubbling, selection, insertion and quick Sort method

1. Bubble Sorting method
* Thinking Analysis: The law, as its name, is like bubbling, each time from the array to take a maximum number out.
* For example: 2,4,1//The First bubble that pops up is 4
* 2,1,4//The Second bubble that pops up is 2
* 1,2,4//The end is like this

$arr =array (1,43,54,62,21,66,32,78,36,76,39);  function Getpao ($arr) {    $len =count ($arr);  Set an empty array to receive the bubbling of bubbles  //That layer loop control needs to bubble the number of rounds for  ($i =1; $i < $len; $i + +)  {//This layer loop is used to control the number of times a number needs to be compared per round for    ($k = 0; $k < $len-$i, $k + +)    {       if ($arr [$k]> $arr [$k +1])        {            $tmp = $arr [$k +1];            $arr [$k +1]= $arr [$k];            $arr [$k]= $tmp;        }}}    

2. Select the sorting method:

Choose a sorting idea: Select a corresponding element at a time and place it in the specified position

function Select_sort ($arr) {//Realize dual loop completion, outer control wheel count, current minimum value. The number of comparisons of the inner control    //$i The current minimum position, the element to be involved in the comparison for    ($i =0, $len =count ($arr); $i < $len-1; $i + +) {        //First assume the location of the minimum value        $p = $i;        $j currently need to compare with which elements, $i behind.        for ($j = $i +1; $j < $len; $j + +) {            //$arr [$p] is the currently known minimum value            if ($arr [$p] > $arr [$j]) {     //compare, find smaller, Record the position of the minimum value, and at the next comparison, the//should be compared with a known minimum value.                $p = $j;            }        }        The location of the current minimum value has been determined and saved to $p. If the location of the minimum value is found to be different from the current assumed position $i, the position is interchangeable if        ($p! = $i) {            $tmp = $arr [$p];            $arr [$p] = $arr [$i];            $arr [$i] = $tmp;        }    }    Return the final result return    $arr;}

3. Insert Sort method

Insert Sort idea: Inserts the element that will be sorted into the specified position of the array that has assumed the sort number.

function Insert_sort ($arr) {    ///distinguish which part is already sorted/    /Which part is not sorted//    find one of the elements that needs to be sorted//    This element is starting with the second element, To the last element is the element that needs to be sorted    //Using a loop can be marked out    //i loop control every time the element needs to be inserted, once the element needs to be inserted control,    //indirectly has divided the array into 2 parts, subscript less than the current (left), is a sorted sequence for    ($i =1, $len =count ($arr); $i < $len; $i + +) {        //Get the element values that are currently being compared.        $tmp = $arr [$i];        Inner loop control compares and inserts        a for ($j = $i-1; $j >=0; $j-) {   //$arr [$i];//the element that needs to be inserted; $arr [$j];//the element to compare            if ($tmp < $ arr[$j]) {                //find the inserted element smaller, swap position                //swap the element behind with the previous element                $arr [$j +1] = $arr [$j];                Set the previous number to the number that currently needs to be swapped                $arr [$j] = $tmp;            } else {                ///If it encounters an element that does not need to be moved           //Because the array is already sorted, the preceding one does not need to be compared again. Break    ;    }}} Insert this element into a sequence that is already sorted.    //Return    $arr;}

4. Quick Sort Method

function Quick_sort ($arr) {
Determine if you need to proceed
$length = count ($arr);
if ($length <= 1) {
return $arr;
}
If there is no return, the number of elements in the array is 1 extra and needs to be sorted
Select a ruler
Select the first element
$base _num = $arr [0];
Iterates through all elements except the ruler, and fits into two arrays in relation to size
Initialize two arrays
$left _array = Array ();//less than the ruler
$right _array = Array ();//greater than the ruler
for ($i =1; $i < $length; $i + +) {
if ($base _num > $arr [$i]) {
Put in the left array
$left _array[] = $arr [$i];
} else {
Put it on the right
$right _array[] = $arr [$i];
}
}
The same sort method for the left and right arrays, respectively.
Call this function recursively and record the result
$left _array = Quick_sort ($left _array);
$right _array = Quick_sort ($right _array);
Merge left ruler right
Return Array_merge ($left _array, Array ($base _num), $right _array);

PHP four basic algorithms: bubbling, selection, insertion and quick Sort method