php PHP中的冒泡排序实现？
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Bubble sort implementation in PHP?
提问by nivanka
I need to do a bubble sort algorithm in PHP.
我需要在 PHP 中做一个冒泡排序算法。
I want to know whether any one has any good examples that I can use, or an open source library which can do this.
我想知道是否有人有任何我可以使用的好例子，或者一个可以做到这一点的开源库。
I have a few spaces in a set (array), i want to fill these spaces with object (a person), so no space can have a male and a female, this why i am trying to find out a bubble sort algorithm.
我在一组（数组）中有几个空间，我想用对象（一个人）填充这些空间，所以没有空间可以有男性和女性，这就是为什么我试图找出冒泡排序算法的原因。
My plan is to fill in any of the available spaces regardless of the gender, and after that sort them separately.
我的计划是不分性别填写任何可用空间，然后分别对它们进行排序。
Thanks.
谢谢。
回答by HymanTurky
function bubble_sort($arr) {
$size = count($arr)-1;
for ($i=0; $i<$size; $i++) {
for ($j=0; $j<$size-$i; $j++) {
$k = $j+1;
if ($arr[$k] < $arr[$j]) {
// Swap elements at indices: $j, $k
list($arr[$j], $arr[$k]) = array($arr[$k], $arr[$j]);
}
}
}
return $arr;
}
For example:
例如：
$arr = array(1,3,2,8,5,7,4,0);
print("Before sorting");
print_r($arr);
$arr = bubble_sort($arr);
print("After sorting by using bubble sort");
print_r($arr);
回答by Rifat
Using bubble sortis a very bad idea. It has complexity of O(n^2).
使用冒泡排序是一个非常糟糕的主意。它的复杂度为O(n^2).
You should use php usort, which is actually a merge sort implementation and guaranteed O(n*log(n))complexity.
您应该使用 php usort，它实际上是一个合并排序实现并保证了O(n*log(n))复杂性。
A sample code from the PHP Manual -
PHP手册中的示例代码 -
function cmp( $a, $b ) {
if( $a->weight == $b->weight ){ return 0 ; }
return ($a->weight < $b->weight) ? -1 : 1;
}
usort($unsortedObjectArray,'cmp');
回答by Sudhir Bastakoti
$numbers = array(1,3,2,5,2);
$array_size = count($numbers);
echo "Numbers before sort: ";
for ( $i = 0; $i < $array_size; $i++ )
echo $numbers[$i];
echo "n";
for ( $i = 0; $i < $array_size; $i++ )
{
for ($j = 0; $j < $array_size; $j++ )
{
if ($numbers[$i] < $numbers[$j])
{
$temp = $numbers[$i];
$numbers[$i] = $numbers[$j];
$numbers[$j] = $temp;
}
}
}
echo "Numbers after sort: ";
for( $i = 0; $i < $array_size; $i++ )
echo $numbers[$i];
echo "n";
回答by Kurt Zhong
function bubble_sort($arr) {
$n = count($arr);
do {
$swapped = false;
for ($i = 0; $i < $n - 1; $i++) {
// swap when out of order
if ($arr[$i] > $arr[$i + 1]) {
$temp = $arr[$i];
$arr[$i] = $arr[$i + 1];
$arr[$i + 1] = $temp;
$swapped = true;
}
}
$n--;
}
while ($swapped);
return $arr;
}
回答by Muhammad Tahir
function bubbleSort(array $arr)
{
$n = sizeof($arr);
for ($i = 1; $i < $n; $i++) {
for ($j = $n - 1; $j >= $i; $j--) {
if($arr[$j-1] > $arr[$j]) {
$tmp = $arr[$j - 1];
$arr[$j - 1] = $arr[$j];
$arr[$j] = $tmp;
}
}
}
return $arr;
}
// Example:
$arr = array(255,1,22,3,45,5);
$result = bubbleSort($arr);
print_r($result);
//====================================================
//------- improved version----------------------------
//====================================================
function bubbleSortImproved(array $arr)
{
$n = sizeof($arr);
for ($i = 1; $i < $n; $i++) {
$flag = false;
for ($j = $n - 1; $j >= $i; $j--) {
if($arr[$j-1] > $arr[$j]) {
$tmp = $arr[$j - 1];
$arr[$j - 1] = $arr[$j];
$arr[$j] = $tmp;
$flag = true;
}
}
if (!$flag) {
break;
}
}
return $arr;
}
// Example:
$arr = array(255,1,22,3,45,5);
$result = bubbleSortImproved($arr);
print_r($result);
回答by Talha Malik
Improved Bubble Sorting enjoy :)
改进的气泡排序享受:)
$sortarr = array(3,5,15,3,2,6,7,50,1,4,5,2,100,9,3,2,6,7,13,18);
echo "<pre>";
// Array to be sorted
print_r($sortarr);
// Sorted Array
print_r(bubble_sort($sortarr));
echo "<pre>";
function bubble_sort($sortarr){
// Bubble sorting
$array_count = count($sortarr);
for($x = 0; $x < $array_count; $x++){
for($a = 0 ; $a < $array_count - 1 ; $a++){
if($a < $array_count ){
if($sortarr[$a] > $sortarr[$a + 1] ){
swap($sortarr, $a, $a+1);
}
}
}
}
return $sortarr;
}
function swap(&$arr, $a, $b) {
$tmp = $arr[$a];
$arr[$a] = $arr[$b];
$arr[$b] = $tmp;
}
回答by Melsi
Maybe someone finds useful my version of Bubble Sort:
也许有人觉得我的冒泡排序版本很有用：
function BubbleSort(&$L)
{
$rm_key = count($L);
while( --$rm_key > -1 )#after this the very first time it will point to the last element
for($i=0; $i<$rm_key; $i++)
if( $L[$i] > $L[$i+1] )
list($L[$i],$L[$i+1]) = array($L[$i+1],$L[$i]);
}
I got the swap idea (using list) from above comment.
我从上面的评论中得到了交换想法（使用列表）。
