DEV Community

loading...
Cover image for Arrays: Left Rotation Code Challenge Solved

Arrays: Left Rotation Code Challenge Solved

rezehnde profile image Marcos Rezende ・1 min read

A left rotation operation on an array shifts each of the array's elements 1 unit to the left. For example, if 2 left rotations are performed on array [1, 2, 3, 4, 5], then the array would become [3, 4, 5, 1, 2].

Given an array a of n integers and a number d, perform d left rotations on the array. Return the updated array to be printed as a single line of space-separated integers.

Function Description
Complete the function rotLeft in the editor below. It should return the resulting array of integers.

rotLeft has the following parameter(s):

  • An array of integers a
  • An integer d, the number of rotations.

Input Format
The first line contains two space-separated integers n and d, the size of a and the number of left rotations you must perform.
The second line contains n space-separated integers a[i].

Constraints
1 <= n <= 10^5
1 <= d <= n
1 <= a[i] <= 10^6

Output Format
Print a single line of n space-separated integers denoting the final state of the array after performing d left rotations.

Sample Input

4
1 2 3 4 5
Enter fullscreen mode Exit fullscreen mode

Sample Output

5 1 2 3 4
Enter fullscreen mode Exit fullscreen mode

Explanation
When we perform left rotations, the array undergoes the following sequence of changes:

[1, 2, 3, 4, 5]
[2, 3, 4, 5, 1]
[3, 4, 5, 1, 2]
[4, 5, 1, 2, 3]
[5, 1, 2, 3, 4]
Enter fullscreen mode Exit fullscreen mode

Solution

function rotLeft($a, $d) {
    $i = 0;
    $m = $d;
    if ($d > sizeof($a)) {
        $m = ($d % sizeof($a));
    }
    while ($i < $m) { 
        $a[] = $a[$i];
        $i++;
    }
    array_splice($a, 0, $m);
    return implode(' ', $a);
}
Enter fullscreen mode Exit fullscreen mode

Discussion (0)

Forem Open with the Forem app