Display display linked list contents.

NewLinkedList factory function.

RemoveKthNodeToTail remove k'th node before tail traverse through the linkedlist with 2 pointers to find k-1'th node then remove the node by manipulating the pointers O(n) time and O(1) space.

Reverse inplace reversal traverse through one time and reverse returns new head O(n) time, O(1) space.

Size returns the Size of the linkedlist O(n) time, O(1) space.