[Leetcode] High Frequency Problems, Hash Table (High Frequency Problems, Hash Table)

Up to now, the total number of LeetCode questions has been 1582题, and it is estimated that the average annual growth will be 300题around in the future . Most people will definitely be 刷不完的, so you have to selectively brush LeetCode.

A generally accepted strategy for brushing questions is 按类别刷题, but each category also has many questions, in a limited time 到底该刷哪些题呢? Individuals sorted out and included the topics in each category according LeetCode官方to each topic given . For topics whose official statistical frequency was too low, they were not included, and finally got this high-frequency topic table.出现频率高频出现

For example, the title of the title number #275and #270in the following figure will be included, and the #275frequency of occurrence is greater than #270; for the title of the title number #1011and #1182, because the occurrence frequency is too low, it will not be included:

Pick up the keyboard and work hard! I wish you all a successful landing! It's not easy to organize, please like it!

---

Hash Table, 81 problems (Hash Table, 81 problems)

Date of data: 2020/03/26 (LeetCode question number at this time: 1582)
Data source: LeetCode official. Questions of different categories are arranged in descending order according to the official frequency (Frequency), and questions with frequency statistics are selected.

Sort	Question number	topic	Passing rate	Difficulty
1	#1	Two Sum	0.479	simple
2	#535	Encode and Decode TinyURL	0.812	medium
3	#3	Longest Substring Without Repeating Characters	0.335	medium
4	#85	Maximal Rectangle	0.449	difficult
5	#37	Sudoku Solver	0.605	difficult
6	#94	Binary Tree Inorder Traversal	0.707	medium
7	#739	Daily Temperatures	0.595	medium
8	#18	4Sum	0.374	medium
9	#136	Single Number	0.66	simple
10	#202	Happy Number	0.576	simple
11	#349	Intersection of Two Arrays	0.685	simple
12	#463	Island Perimeter	0.658	simple
13	#30	Substring with Concatenation of All Words	0.299	difficult
14	#632	Smallest Range Covering Elements from K Lists	0.356	difficult
15	#718	Maximum Length of Repeated Subarray	0.492	medium
16	#76	Minimum Window Substring	0.355	difficult
17	#500	Keyboard Row	0.685	simple
18	#187	Repeated DNA Sequences	0.44	medium
19	#560	Subarray Sum Equals K	0.443	medium
20	#447	Number of Boomerangs	0.572	simple
21	#49	Group Anagrams	0.612	medium
22	#138	Copy List with Random Pointer	0.476	medium
23	#409	Longest Palindrome	0.549	simple
24	#690	Employee Importance	0.575	simple
25	#204	Count Primes	0.329	simple
26	#347	Top K Frequent Elements	0.607	medium
27	#525	Contiguous Array	0.416	medium
28	#726	Number of Atoms	0.437	difficult
29	#36	Valid Sudoku	0.588	medium
30	#454	4Sum 2	0.543	medium
31	#1044	Longest Duplicate Substring	0.175	difficult
32	#781	Rabbits in Forest	0.543	medium
33	#594	Longest Harmonious Subsequence	0.461	simple
34	#389	Find the Difference	0.612	simple
35	#336	Palindrome Pairs	0.331	困难
36	#149	Max Points on a Line	0.213	困难
37	#217	Contains Duplicate	0.518	简单
38	#290	Word Pattern	0.423	简单
39	#242	Valid Anagram	0.591	简单
40	#219	Contains Duplicate II	0.379	简单
41	#274	H-Index	0.379	中等
42	#350	Intersection of Two Arrays II	0.474	简单
43	#575	Distribute Candies	0.66	简单
44	#205	Isomorphic Strings	0.473	简单
45	#299	Bulls and Cows	0.472	简单
46	#438	Find All Anagrams in a String	0.42	中等
47	#645	Set Mismatch	0.415	简单
48	#355	Design Twitter	0.367	中等
49	#508	Most Frequent Subtree Sum	0.627	中等
50	#720	Longest Word in Dictionary	0.461	简单
51	#166	Fraction to Recurring Decimal	0.258	中等
52	#648	Replace Words	0.536	中等
53	#1001	Grid Illumination	0.271	困难
54	#387	First Unique Character in a String	0.44	简单
55	#451	Sort Characters By Frequency	0.63	中等
56	#554	Brick Wall	0.358	中等
57	#676	Implement Magic Dictionary	0.565	中等
58	#692	Top K Frequent Words	0.497	中等
59	#966	Vowel Spellchecker	0.383	中等
60	#711	Number of Distinct Islands II	0.561	困难
61	#381	Insert Delete GetRandom O(1) - Duplicates allowed	0.369	困难
62	#599	Minimum Index Sum of Two Lists	0.502	simple
63	#609	Find Duplicate File in System	0.521	medium
64	#244	Shortest Word Distance II	0.494	medium
65	#380	Insert Delete GetRandom O(1)	0.478	medium
66	#311	Sparse Matrix Multiplication	0.728	medium
67	#325	Maximum Size Subarray Sum Equals k	0.477	medium
68	#159	Longest Substring with At Most Two Distinct Characters	0.51	medium
69	#314	Binary Tree Vertical Order Traversal	0.539	medium
70	#359	Logger Rate Limiter	0.691	simple
71	#694	Number of Distinct Islands	0.457	medium
72	#358	Rearrange String k Distance Apart	0.341	difficult
73	#249	Group Shifted Strings	0.604	medium
74	#288	Unique Word Abbreviation	0.314	medium
75	#734	Sentence Similarity	0.488	simple
76	#340	Longest Substring with At Most K Distinct Characters	0.464	difficult
77	#266	Palindrome Permutation	0.631	simple
78	#624	Maximum Distance in Arrays	0.406	simple
79	#170	Two Sum III - Data structure design	0.407	simple
80	#356	Line Reflection	0.285	medium
81	#246	Strobogrammatic Number	0.464	simple

Related/reference links

leetcode-cn
leetcode