算法工程师-机器学习-数据科学家面试准备2- Leetcode

https://github.com/LongxingTan/Machine-learning-interview

• 算法工程师-机器学习-数据科学家面试准备1- 概述 外企和国外公司、春招、秋招
• 算法工程师-机器学习-数据科学家面试准备2- Leetcode 300
• 算法工程师-机器学习-数据科学家面试准备3-系统设计
• 算法工程师-机器学习-数据科学家面试准备4-ML系统设计

整体目标

• lc: 总量600～800，其中高频300熟悉，且能bug free的写出多种解法
• ml: 熟悉推荐系统与NLP，常见场景系统设计，模型发展的脉络，常用模型的理论与优化

2023-九月刷题

序号	日期	题目	评论
1	0918	33. Search in Rotated Sorted Array	1. 有一半必然存在单调，二分 2. 各种边界
2	0918	209. Minimum Size Subarray Sum	滑动窗口，理论上一次循环，右边界在循环
3	0918	59. Spiral Matrix II	左右都可以闭区间，否则开区间注意填充奇书中心值
4	0919	707. Design Linked List	边界、循环等细节
5	0919	24. Swap Nodes in Pairs	画图模拟，几个细节容易出错
6	0919	19. Remove Nth Node From End of List	快慢指针
7	0920	142. Linked List Cycle II	可以采用列表记录，或快慢指针，快指针回到起点
8	0920	454. 4Sum II	记录前两个出现的和次数，再从后两个和中哈希查找
9	0920	15. 3Sum	注意去重
10	0921	18. 4Sum	和3sum基本一样，去重
11	0921	151. Reverse Words in a String	split 双指针
12	0921	150. Evaluate Reverse Polish Notation	栈，字符串转实际运算符
13	0922	239. Sliding Window Maximum	单调队列，和单调栈结合起来看
14	0922	347. Top K Frequent Elements	字典或heap
15	0922	102. Binary Tree Level Order Traversal	bfs
16	0923	107. Binary Tree Level Order Traversal II	bfs
17	0923	199. Binary Tree Right Side View	bfs
18	0923	429. N-ary Tree Level Order Traversal	bfs
19	0923	515. Find Largest Value in Each Tree Row	bfs
20	0923	116. Populating Next Right Pointers in Each Node	bfs
21	0923	117. Populating Next Right Pointers in Each Node II	bfs
22	0924	513. Find Bottom Left Tree Value	bfs
23	0924	106. Construct Binary Tree from Inorder and Postorder Traversal	构造，从root开始，前序
24	0924	105. Construct Binary Tree from Preorder and Inorder Traversal	构造，从root开始，前序
25	0925	654. Maximum Binary Treel	构造
26	0925	98. Validate Binary Search Tree	中序
27	0925	236. Lowest Common Ancestor of a Binary Tree	祖先含义需要转化为理解
28	0925	235. Lowest Common Ancestor of a Binary Search Tree
29	0926	701. Insert into a Binary Search Tree
30	0926	450. Delete Node in a BST
31	0926	669. Trim a Binary Search Tree
32	0927	538. Convert BST to Greater Tree	从右向左的中序遍历
33	0927	77. Combinations	回溯：n叉树，树的宽度和深度；模版；增加path[:] copy
34	0927	216. Combination Sum III
35	0928	17. Letter Combinations of a Phone Number	理解这时树的宽度、深度分别对应什么
36	0928	39. Combination Sum
37	0928	40. Combination Sum II	注意如何去重，排序，在单层逻辑前判断相等的话略过
38	0929	131. Palindrome Partitioning
39	0929	93. Restore IP Addresses
40	0929	78. Subsets	回溯，前面的都是叶节点归入结果，子集是全部节点进入结果集
41	0929	90. Subsets II	注意根据排序，和宽度时如何去重
42	0929	491. Non-decreasing Subsequences	按树宽度去重，按set或hash去重，结果筛选
43	0929	46. Permutations	树往下的时候，需要从剩余集合中选择，因此排列问题需要标记visited
44	0929	47. Permutations II	去重: 叶节点+visit判断
45	0930	332. Reconstruct Itinerary
46	0930	51. N-Queens
47	0930	37. Sudoku Solver
48	0930	376. Wiggle Subsequence
49	0930	53. Maximum Subarray
50	0930	122. Best Time to Buy and Sell Stock II
51	1008	55. Jump Game	只记录覆盖范围并更新
52	1008	45. Jump Game II	我会更习惯动态规划解法
53	1008	134. Gas Station	贪心不好想，先掌握暴力模拟
54	1008	135. Candy	两次模拟
55	1008	406. Queue Reconstruction by Height	排序的key是关键
56	1008	452. Minimum Number of Arrows to Burst Balloons
57	1008	435. Non-overlapping Intervals
58	1008	763. Partition Labels
59	1009	56. Merge Intervals
60	1009	738. Monotone Increasing Digits	字符串不能直接给一位赋值，list(str(n))
61	1009	968. Binary Tree Cameras
62	1010	62. Unique Paths	2d 简单动态规划
63	1010	63. Unique Paths II	障碍物初始化时，只有障碍物前的才会1
64	1010	343. Integer Break	通过举例过程想到动态规划
65	1010	96. Unique Binary Search Trees	通过举例过程想到动态规划，和上一题有点像
66	1011	416. Partition Equal Subset Sum	要如何想到是背包？
67	1011	1049. Last Stone Weight II
68	1011	494. Target Sum
69	1011	474. Ones and Zeroes	??
70	1012	518. Coin Change II
71	1012	377. Combination Sum IV
72	1012	322. Coin Change	经典题目
73	1013	279. Perfect Squares
74	1013	139. Word Break	如何想到用背包？
75	1013	198. House Robber
76	1014	213. House Robber II
77	1014	337. House Robber III	树形DP
78	1014	122. Best Time to Buy and Sell Stock II	动归，第2维是状态，这里是持有或不持有
79	1014	123. Best Time to Buy and Sell Stock III	完成2笔，就是0/1/2/3/4
80	1014	188. Best Time to Buy and Sell Stock IV	123的2进一步参数化，for
81	1014	309. Best Time to Buy and Sell Stock with Cooldown	注意划分多个状态及状态见转移
82	1014	714. Best Time to Buy and Sell Stock with Transaction Fee	和122类似，卖出时加上手续费
83	1015	300. Longest Increasing Subsequence
84	1015	718. Maximum Length of Repeated Subarray
85	1015	1143. Longest Common Subsequence
86	1015	1035. Uncrossed Lines
87	1015	53. Maximum Subarray
88	1015	115. Distinct Subsequences
89	1015	583. Delete Operation for Two Strings
90	1015	72. Edit Distance
91	1015	647. Palindromic Substrings
92	1015	516. Longest Palindromic Subsequence
93	1016	739. Daily Temperatures	单调栈，没有很理解其初始化，自己独立写可能还是会出问题
94	1017	503. Next Greater Element II
95	1017	42. Trapping Rain Water
96	1017	84. Largest Rectangle in Histogram
97	1018	797. All Paths From Source to Target
98	1018	200. Number of Islands
99	1019	1020. Number of Enclaves
100	1019	417. Pacific Atlantic Water Flow
101	1020	130. Surrounded Regions

2023十二月刷题

序号	日期	题目	评论
1	1208	33. Search in Rotated Sorted Array	1. 有一半必然存在单调，二分 2. 各种边界

二月计划

序号	日期	评论
1	0213	BFS+拓扑，阅读完FlagE结构
2	0214	string + stack + queue
2	0215	dynamic programming
2	0216	greedy
2	0217	小结, +推荐系统架构
2	0218	LLM + retrievals架构

其他

• 代码随想录刷题总结
  leetcode 有个 mock 的功能，每次全屏
  查看discussion

Curated-List-of-Top-75-LeetCode-Questions-to-Save-Your-Time-OaM1orEU

列表

• https://blog.youkuaiyun.com/weixin_38812492/article/details/128145865?spm=1001.2014.3001.5501-

二叉树：

• https://blog.youkuaiyun.com/weixin_38812492/article/details/126925242?spm=1001.2014.3001.5502-

剑指offer

• https://blog.youkuaiyun.com/weixin_38812492/article/details/113056282?spm=1001.2014.3001.5502-

Remove Duplicates from Sorted Array

Given a sorted array, remove the duplicates in place such that each element appear only once and return the new length.

Do not allocate extra space for another array, you must do this in place with constant memory.

For example, Given input array A = [1,1,2],

Your function should return length = 2, and A is now [1,2].

排序而且有重复，那么

• 记录下一个不重复的数值的位置，并自动向后移
• 找到其中新的不重复数值。或者单独一个值记录，或者根据前后是否发生变化

Remove Duplicates from Sorted Array II

Follow up for "Remove Duplicates": What if duplicates are allowed at most twice?

For example, given sorted array A = [1,1,1,2,2,3], your function should return length = 5, and A is now [1,1,2,2,3]