{ "data": { "question": { "questionId": "1337", "questionFrontendId": "1206", "boundTopicId": null, "title": "Design Skiplist", "titleSlug": "design-skiplist", "content": "
Design a Skiplist without using any built-in libraries.
\n\nA 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:
\nArtyom Kalinin [CC 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
\n\nImplement 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.
\n\n\n
Example 1:
\n\n\nInput\n["Skiplist", "add", "add", "add", "search", "add", "search", "erase", "erase", "search"]\n[[], [1], [2], [3], [0], [4], [1], [0], [1], [1]]\nOutput\n[null, null, null, null, false, null, true, false, true, false]\n\nExplanation\nSkiplist skiplist = new Skiplist();\nskiplist.add(1);\nskiplist.add(2);\nskiplist.add(3);\nskiplist.search(0); // return False\nskiplist.add(4);\nskiplist.search(1); // return True\nskiplist.erase(0); // return False, 0 is not in skiplist.\nskiplist.erase(1); // return True\nskiplist.search(1); // return False, 1 has already been erased.\n\n
\n
Constraints:
\n\n0 <= num, target <= 2 * 104
5 * 104
calls will be made to search
, add
, and erase
.Compiled with clang 11
using the latest C++ 20 standard.
Your code is compiled with level two optimization (-O2
). AddressSanitizer is also enabled to help detect out-of-bounds and use-after-free bugs.
Most standard library headers are already included automatically for your convenience.
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Python 2.7.12
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Most libraries are already imported automatically for your convenience, such as array, bisect, collections. If you need more libraries, you can import it yourself.
\\r\\n\\r\\nFor Map/TreeMap data structure, you may use sortedcontainers library.
\\r\\n\\r\\nNote that Python 2.7 will not be maintained past 2020. For the latest Python, please choose Python3 instead.
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\\r\\n\\r\\nFor hash table operations, you may use uthash. \\\"uthash.h\\\" is included by default. Below are some examples:
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Node.js 16.13.2
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Your code is run with --harmony
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lodash.js library is included by default.
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Go 1.21
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Most libraries are already imported automatically for your convenience, such as array, bisect, collections. If you need more libraries, you can import it yourself.
\\r\\n\\r\\nFor Map/TreeMap data structure, you may use sortedcontainers library.
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Kotlin 1.9.0
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Rust 1.58.1
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With bcmath module
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Dart 2.17.3
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