func NewStack() Stack { return stack }

** Push element x to the back of queue. */

** Initialize your data structure here. */

** Returns whether the queue is empty. */

** Get the front element. */

** Removes the element from in front of queue and returns that element. */

abab bas ab* b.*

0 – found -1 – delete next

** Initialize your data structure here. */

** Get a random element from the set. */

** Inserts a value to the set. Returns true if the set did not already contain the specified element. */

** Removes a value from the set. Returns true if the set contained the specified element. */

Deserializes your encoded data to tree.