Given an array, the task is to rotate an array to the left by d position in PHP. Array left rotation by d positions involves shifting array elements to the left by d positions.

Examples:

Input: arr = {1, 2, 3, 4, 5, 6, 7}, d = 2
Output: 3 4 5 6 7 1 2

Input: arr = {3, 4, 5, 6, 7, 1, 2}, d = 2
Output: 5 6 7 1 2 3 4

Using Array Slice() Function

In this approach, first, we will slice the array into two parts - one from index d to the end, and the other from the start to index d-1 using the array_slice() method. Then, we will concatenate these two parts in reverse order using the array_merge() method to obtain the left rotated array.

Example: This example uses array slicing technique to left rotate array by d positions.

<?php

  function leftRotateArray($arr, $d) {
    $newArray = array_merge(
        array_slice($arr, $d), 
        array_slice($arr, 0, $d)
    );
  
    return $newArray;
}

// Driver code
$arr = [1, 2, 3, 4, 5];
$d = 2;

$result = leftRotateArray($arr, $d);

// Print the array elements
foreach ($result as $element) {
    echo $element . " ";
}

?>

3 4 5 1 2 

Using array_shift() and array_push() Functions

In this approach, we iterate through the array d times. In each iteration, we use array_shift() to remove the first element of the array and array_push() to add it to the end. This process effectively shifts each element d positions to the left. Finally, we return the modified array.

Example: This example uses array_shift() and array_push() functions to left rotate array by d positions.

<?php
  
function leftRotate($arr, $d) {
    for ($i = 0; $i < $d; $i++) {
        $element = array_shift($arr);
        array_push($arr, $element);
    }
    return $arr;
}

// Driver code
$arr = [1, 2, 3, 4, 5, 6, 7];
$d = 3;

$result = leftRotate($arr, $d);

foreach ($result as $element) {
    echo $element . " ";
}

?>

4 5 6 7 1 2 3 

Using a Temporary Array

In this approach, we:

• Store the first d elements in a temporary array.
• Shift the remaining elements in the original array to the left.
• Copy the elements from the temporary array to the end of the original array.

Example: This example uses a temporary array to left rotate the array by d positions.

<?php

function leftRotateWithTempArray($arr, $d) {
    $n = count($arr);
    $temp = array_slice($arr, 0, $d); // Step 1: Store the first d elements in a temporary array

    // Step 2: Shift the remaining elements to the left
    for ($i = $d; $i < $n; $i++) {
        $arr[$i - $d] = $arr[$i];
    }

    // Step 3: Copy the elements from the temporary array to the end
    for ($i = 0; $i < $d; $i++) {
        $arr[$n - $d + $i] = $temp[$i];
    }

    return $arr;
}

// Driver code
$arr = [1, 2, 3, 4, 5, 6, 7];
$d = 2;

$result = leftRotateWithTempArray($arr, $d);

// Print the array elements
foreach ($result as $element) {
    echo $element . " ";
}

?>

3 4 5 6 7 1 2