What is the principle and implementation of the insertion sort algorithm in PHP?

The principle and implementation of the insertion sort algorithm in PHP

Insertion sort is a common sorting algorithm. Its core idea is to insert an element into in an already ordered sequence. In PHP, we can implement the insertion sort algorithm through simple numerical exchange. This article will introduce the principle and implementation of insertion sort in detail, and provide specific code examples.

Principle:

1. Select an element from the unsorted sequence and insert it into the appropriate position of the sorted sequence.
2. Determine where the element should be inserted by comparing the element to be inserted with the elements in the sorted sequence.
3. Repeat steps 1 and 2 until the unsorted sequence is empty.

Implementation method:
The following is a code example to implement the insertion sort algorithm in PHP:

function insertionSort($array)
{
    $length = count($array);

    for ($i = 1; $i < $length; $i++) {
        $key = $array[$i];
        $j = $i - 1;

        // 将当前元素与已排序序列中的元素比较，找到合适的插入位置
        while ($j >= 0 && $array[$j] > $key) {
            $array[$j + 1] = $array[$j];
            $j--;
        }

        $array[$j + 1] = $key;
    }

    return $array;
}

// 示例用法
$data = [4, 2, 7, 1, 9, 5];
$sortedData = insertionSort($data);
print_r($sortedData);

In the above code, the insertionSort function accepts an array as parameters and returns a sorted array. During the sorting process, we use a $key variable to save the current element to be inserted. In each comparison, the element larger than the element in the sorted sequence is moved one position to the right until a suitable one is found. Insert position.

In the example usage, we define an array to be sorted $data and pass it to the insertionSort function. Finally, print the sorted results through print_r($sortedData).

Summary:
Insertion sort is a simple but efficient sorting algorithm. By inserting elements into the sorted sequence one by one, you can quickly get an ordered sequence. In PHP, we can implement the insertion sort algorithm using simple numerical exchange. I hope this article will be helpful in understanding the principles and implementation of insertion sort.

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