Implementation steps of insertion sort algorithm in PHP

Insertion sort algorithm implementation steps in PHP

Insertion sort is a simple and intuitive sorting algorithm. It inserts unsorted data into the sorted sequence one by one by constructing an ordered sequence, thereby Get an ordered sequence. In PHP, we can implement the insertion sort algorithm through the following steps.

Step 1: Define a function insertionSort, which receives an array to be sorted as a parameter.

function insertionSort($arr) {
  $n = count($arr);
  for ($i = 1; $i < $n; $i++) {
    $key = $arr[$i];
    $j = $i - 1;

    while ($j >= 0 && $arr[$j] > $key) {
      $arr[$j + 1] = $arr[$j];
      $j = $j - 1;
    }
    $arr[$j + 1] = $key;
  }

  return $arr;
}

Step 2: Call the insertionSort function in the main program and pass in the array to be sorted.

$unsortedArray = [5, 2, 1, 7, 3];
$sortedArray = insertionSort($unsortedArray);

Step 3: Define a for loop to output the sorted array.

$n = count($sortedArray);
for ($i = 0; $i < $n; $i++) {
  echo $sortedArray[$i] . " ";
}

The complete code is as follows:

The above code implements the insertion sort algorithm. The core idea of ​​the algorithm is to divide the array to be sorted into two parts, sorted and unsorted, and obtain an ordered result by inserting unsorted elements into the sorted part one by one. In the code, we use a for loop to traverse the array to be sorted and insert the current element into the appropriate position. The inner while loop is used to continuously compare and move the elements of the sorted section until the appropriate position is found.

The time complexity of the insertion sort algorithm is O(n^2), where n represents the length of the array to be sorted. Since the algorithm only involves comparison and movement operations of adjacent elements, the space complexity is O(1) and it is an in-place sorting algorithm.

Summary: Through the above steps, we successfully implemented the insertion sort algorithm in PHP. The algorithm is simple and effective and suitable for sorting small-scale data. In practical applications, if the array to be sorted is large or higher performance is required, other faster sorting algorithms can be considered.

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