Sorting Algorithms using PHP

bubblesort.php

<?php

/**
 * BubbleSort in PHP
 *
 * @param  array $data
 * @return array
 */
function bubblesort ($data) {
    $length = count($data);

    for ($i = 0; $i < $length; $i++) {
        for ($j = 0; $j < ($length - 1); $j++) {
            if ($data[$i] < $data[$j]) {
                $tmp = $data[$i];

                $data[$i] = $data[$j];
                $data[$j] = $tmp;
            }
        }
    }

    return $data;
}

$data = [265, 7, 3, 2, 9, 8, 7, 12, 234, 43, 856, 3, 12, 0, 332, 479];

$sort = bubblesort($data);

echo "<pre>";
print_r($sort);
echo "</pre>";
exit;

insertionsort.php

<?php

/**
 * InsertionSort in PHP
 *
 * @param  array $data
 * @return array
 */
function insertionsort ($data) {
    $length = count($data);

    for ($i = 1; $i < $length; $i++) {
        for ($j = ($i - 1); $j >= 0; $j--) {
            if ($data[$j] > $data[$j + 1]) {
                $tmp = $data[$j + 1];

                $data[$j+1] = $data[$j];
                $data[$j] = $tmp;
            }
        }
    }

    return $data;
}

$data = [265, 7, 3, 2, 9, 8, 7, 12, 234, 43, 856, 3, 12, 0, 332, 479];

$sort = insertionsort($data);

echo "<pre>";
print_r($sort);
echo "</pre>";
exit;

mergesort.php

<?php

/**
 * MergeSort in PHP
 *
 * @param  array $data
 * @return array
 */
function mergesort ($data) {
    $length = count($data);

    if ($length == 1) {
        return $data;
    }

    $mid = $length /2;
    $left = array_slice($data, 0, $mid);
    $right = array_slice($data, $mid, $length);

    /**
     * Natural way of splitting data in half, without using internal
     * functions of php
     * @var array
     */
    /*$left = [];
    $right = [];

    for ($i = 0; $i < $length; $i++) {
        if ($i < $length/2) {
            $left[] = $data[$i];
        } else {
            $right[] = $data[$i];
        }
    }*/

    $result = [];
    $left = mergesort($left);
    $right = mergesort($right);

    /**
     * MERGE
     *
     * Seen other versions that breaks this functionality into a lone
     * function, but not sure I understand why
     */
    while (count($left) > 0 && count($right) > 0) {
        if ($left[0] <= $right[0]) {
            $result[] = array_shift($left);
        } else {
            $result[] = array_shift($right);
        }
    }

    while (count($left) > 0) {
        $result[] = array_shift($left);
    }

    while (count($right) > 0) {
        $result[] = array_shift($right);
    }

    return $result;
}

$data = [265, 7, 3, 2, 9, 8, 7, 12, 234, 43, 856, 3, 12, 0, 332, 479, 99];

$sort = mergesort($data);

echo "<pre>";
print_r($sort);
echo "</pre>";
exit;

quicksort.php

<?php

/**
 * Quick Sort in PHP
 *
 * This sort algorithms is close to 80% slower than sort() when
 * sorting ~10,000 integers. Use internal functions.
 *
 * @param  array $data
 * @return array
 */
function quicksort ($data) {
    $length = count($data);

    if ($length < 2) {
        return $data;
    }

    // Taking the first element in the array is
    $pivot = $data[0];
    $left = [];
    $right = [];

    for ($i=1; $i < $length; $i++) {
        if ($data[$i] < $pivot) {
            $left[] = $data[$i];
        } else {
            $right[] = $data[$i];
        }
    }

    return array_merge(quicksort($left), [$pivot], quicksort($right));
}


$data = [265, 7, 3, 2, 9, 8, 7, 12, 234, 43, 856, 3, 12, 0, 332, 479, 99];

$sort = quicksort($data);

echo "<pre>";
print_r($sort);
echo "</pre>";
exit;