[Leetcode] High Frequency Problems, Backtracking (High Frequency Problems, Backtracking)

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!

---

Backtracking, 37 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	#22	Generate Parentheses	0.737	medium
2	#46	Permutations	0.745	medium
3	#17	Letter Combinations of a Phone Number	0.53	medium
4	#37	Sudoku Solver	0.605	difficult
5	#93	Restore IP Addresses	0.462	medium
6	#10	Regular Expression Matching	0.269	difficult
7	#51	N-Queens	0.686	difficult
8	#78	Subsets	0.769	medium
9	#39	Combination Sum	0.686	medium
10	#131	Palindrome Partitioning	0.665	medium
11	#77	Combinations	0.733	medium
12	#357	Count Numbers with Unique Digits	0.507	medium
13	#47	Permutations II	0.578	medium
14	#89	Gray Code	0.679	medium
15	#401	Binary Watch	0.52	simple
16	#216	Combination Sum III	0.705	medium
17	#79	Word Search	0.41	medium
18	#306	Additive Number	0.313	medium
19	#52	N-Queens II	0.777	difficult
20	#526	Beautiful Arrangement	0.609	medium
21	#90	Subsets II	0.594	medium
22	#60	Permutation Sequence	0.486	medium
23	#351	Android Unlock Patterns	0.59	medium
24	#44	Wildcard Matching	0.271	difficult
25	#40	Combination Sum II	0.609	medium
26	#691	Stickers to Spell Word	0.448	difficult
27	#212	Word Search II	0.397	difficult
28	#411	Minimum Unique Word Abbreviation	0.458	difficult
29	#211	Add and Search Word - Data structure design	0.434	medium
30	#140	Word Break II	0.376	difficult
31	#126	Word Ladder II	0.318	difficult
32	#291	Word Pattern II	0.502	difficult
33	#320	Generalized Abbreviation	0.611	medium
34	#294	Flip Game II	0.569	medium
35	#267	Palindrome Permutation II	0.395	medium
36	#425	Word Squares	0.524	difficult
37	#254	Factor Combinations	0.553	medium

Related/reference links

leetcode-cn
leetcode