Kata

Linked Lists - Append

Write an Append() function which appends one linked list to another. The head of the resulting list should be returned.

var listA = 1 -> 2 -> 3 -> null
var listB = 4 -> 5 -> 6 -> null
append(listA, listB) === 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> null

listA = 1 -> 2 -> 3 -> null
listB = 4 -> 5 -> 6 -> null
append(listA, listB) == 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> null

$list_a = 1 -> 2 -> 3 -> NULL;
$list_b = 4 -> 5 -> 6 -> NULL;
append($list_a, $list_b) // returns 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> NULL

list_a = 1 -> 2 -> 3 -> nil
list_b = 4 -> 5 -> 6 -> nil
append(list_a, list_b) == 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> nil

If both listA and listB are null/NULL/None/nil, return null/NULL/None/nil. If one list is null/NULL/None/nil and the other is not, simply return the non-null/NULL/None/nil list.

The push() and buildOneTwoThree() (build_one_two_three() in PHP and ruby) functions need not be redefined. The Node class is also predefined for you in PHP.

/* PHP Only */
class Node {
  public $data, $next;
  public function __construct($data, $next = NULL) {
    $this->data = $data;
    $this->next = $next;
  }
}

Related Kata in order of expected completion (increasing difficulty):
 Linked Lists - Push & BuildOneTwoThree
 Linked Lists - Length & Count
 Linked Lists - Get Nth Node
Linked Lists - Insert Nth Node
Linked Lists - Sorted Insert
Linked Lists - Insert Sort
Linked Lists - Append
Linked Lists - Remove Duplicates
Linked Lists - Move Node
Linked Lists - Move Node In-place
Linked Lists - Alternating Split
Linked Lists - Front Back Split
Linked Lists - Shuffle Merge
Linked Lists - Sorted Merge
Linked Lists - Merge Sort
Linked Lists - Sorted Intersect
Linked Lists - Iterative Reverse
Linked Lists - Recursive Reverse

Inspired by Stanford Professor Nick Parlante's excellent Linked List teachings.