Package g1201_1300.s1206_design_skiplist

Class Skiplist

java.lang.Object

g1201_1300.s1206_design_skiplist.Skiplist

public class Skiplist
extends Object

1206 - Design Skiplist\. Hard Design a **Skiplist** without using any built-in libraries. A **skiplist** is a data structure that takes `O(log(n))` time to add, erase and search. Comparing with treap and red-black tree which has the same function and performance, the code length of Skiplist can be comparatively short and the idea behind Skiplists is just simple linked lists. For example, we have a Skiplist containing `[30,40,50,60,70,90]` and we want to add `80` and `45` into it. The Skiplist works this way:  Artyom Kalinin [CC BY-SA 3.0], via [Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Skip_list_add_element-en.gif "Artyom Kalinin [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons") You can see there are many layers in the Skiplist. Each layer is a sorted linked list. With the help of the top layers, add, erase and search can be faster than `O(n)`. It can be proven that the average time complexity for each operation is `O(log(n))` and space complexity is `O(n)`. See more about Skiplist: [https://en.wikipedia.org/wiki/Skip\_list](https://en.wikipedia.org/wiki/Skip_list) Implement the `Skiplist` class: * `Skiplist()` Initializes the object of the skiplist. * `bool search(int target)` Returns `true` if the integer `target` exists in the Skiplist or `false` otherwise. * `void add(int num)` Inserts the value `num` into the SkipList. * `bool erase(int num)` Removes the value `num` from the Skiplist and returns `true`. If `num` does not exist in the Skiplist, do nothing and return `false`. If there exist multiple `num` values, removing any one of them is fine. Note that duplicates may exist in the Skiplist, your code needs to handle this situation. **Example 1:** **Input** ["Skiplist", "add", "add", "add", "search", "add", "search", "erase", "erase", "search"] [ [], [1], [2], [3], [0], [4], [1], [0], [1], [1]] **Output:** [null, null, null, null, false, null, true, false, true, false] **Explanation:** Skiplist skiplist = new Skiplist(); skiplist.add(1); skiplist.add(2); skiplist.add(3); skiplist.search(0); // return False skiplist.add(4); skiplist.search(1); // return True skiplist.erase(0); // return False, 0 is not in skiplist. skiplist.erase(1); // return True skiplist.search(1); // return False, 1 has already been erased. **Constraints:** * 0 <= num, target <= 2 * 104 * At most 5 * 104 calls will be made to `search`, `add`, and `erase`.

Constructor Summary

Constructors

Constructor	Description
Skiplist()
Skiplist(int size)

Method Summary

Modifier and Type	Method	Description
void	add(int num)
boolean	erase(int num)
boolean	search(int target)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Skiplist

public Skiplist()

Skiplist

public Skiplist(int size)

Method Detail

search

public boolean search(int target)

add

public void add(int num)

erase

public boolean erase(int num)