PHP insertion sorting to implement an array sort instance _php tutorial

Example of array sorting using PHP insertion sorting

This article mainly introduces the PHP insertion sorting method to achieve array sorting, example analysis of the insertion sorting method of the principle and specific implementation skills, with a certain reference value, the need for friends can refer to the next

In this paper, we describe the method of inserting sorting in PHP to realize array sorting. Share to everyone for your reference. The specific analysis is as follows:

The basic idea of inserting the sorting method is to illustrate the same case, or to $arr = Array (2,6,3,9), from the large to the small sort.

Implementation principle: Suppose (not actually created) there is an ordered array $arr = Array (2), with $arr[1]=6 to compare it, if 6>2, by moving $arr[0] back to the $arr[1] position, and 6 inserted into the $arr[0] position. Then, $arr [2]=3 and $arr[1]=2, 3>2, then $arr[1]=2 continue to move to $arr[2] position, the original $arr[3]=3 inserted into the $arr[1] position, and then continue to insert 9 into the close position, the result is (9,6,3,2). It is also possible to sort by count ($arr)-1 cycles.

Code Law Analysis:

The first big cycle: $[1] and $[0] than;
The second big cycle: $[2] and $[1] than, $[1] and $[0] than;
The third big cycle: $[3] and $[2] than, $[2] and $[1] than, $[1] and $[0] than;

PHP code, using the function encapsulation, to facilitate the use of

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Function Insertsort (& $arr) { for ($i =1; $i<>< p=""> <> $insertVal is the number that is ready to be inserted for ($j = $i; $j >0; $j--) { if ($arr [$j]> $arr [$j-1]) { $insertVal = $arr [$j]; $arr [$j] = $arr [$j-1]; $arr [$j-1] = $insertVal; } } } } $myarr = Array (2,6,3,9); Insertsort ($myarr); echo " "; Print_r ($myarr); ?>

Code Implementation Analysis:

First big cycle:

$i =1 Array (2,6,3,9)
$j = 1 Perform 6 and 2 ratios: $arr [1]=2; $arr [0]=6, Get (6,2,3,9)

Second big cycle:

$i =2 Array (6,2,3,9)
$j = 2 performs 3 and 2 ratios: becomes $arr[2]=2, $arr [1]=3, gets (6,3,2,9)
$j--, $j = 1 Execute $arr[1] and $arr[0] ratio: condition not established

The third big cycle:

$i =3 Array (6,3,2,9)
$j = 3 performs 9 and 2 ratios: becomes $arr[3]=2, $arr [2]=9, gets (6,3,9,2)
$j--, $j = 2 Perform 9 and 3 ratios: Become $arr[2]=3, $arr [1]=9, Get (6,9,3,2)
$j--, $j = 1 Perform 9 and 6 ratios: Become $arr[1]=5, $arr [0]=9, Get (9,6,3,2)

I hope this article is helpful to everyone's PHP programming.

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