[第三期活动] 在职刷题打卡，目标工作日一天2题，周末一天5题

9/19+9/20 刷面经
Hackerrank: metals
Hackerrank: team formation
2道 处理http request string
895. Maximum Frequency Stack  (frequency stack + stack storing number)
139. Word Break
140. Word Break II
面经题 Find Strings That Differ by 1 Character, brute force
面经题 array partition:
Given an integer array, the values of the array need to separated into two subsets A and B whose intersection is null and whose unions the entire array.
The sum of values in set A must be strictly greater than sum of values in set B, and number of elements in set A must be minimal. Return the values in set A.
341. Flatten Nested List Iterator (stack)
394. Decode String

Stage II : 分类各个击破
day15-09/21-二分的边界还是处理的不是很好，基本很难一遍过，都得慢慢调一会儿……感觉面试遇到这种题还是得跪。。ss跪了，随便搜个vpn ip都能被封，我大天朝真的是厉害了
graph：
1. 133. Clone Graph
binary search:
1. 50. Pow(x, n)
2. 74. Search a 2D Matrix
3. 33. Search in Rotated Sorted Array
4. 81. Search in Rotated Sorted Array II
5. 153. Find Minimum in Rotated Sorted Array
6. 154. Find Minimum in Rotated Sorted Array II
7. 215. Kth Largest Element in an Array
8. 240. Search a 2D Matrix II
9. 162. Find Peak Element
10. 278. First Bad Version
11. 69. Sqrt(x)
12. 374. Guess Number Higher or Lower

# Day 2
491. Increasing Subsequences
646. Maximum Length of Pair Chain

day 16
因为改简历和准备常见问题的答案，刷题断了些……继续了
Factor Combinations
Shortest Word Distance

# Day_20
Array
Best Time to Buy and Sell Stock I, II, III, IV,
Best Time to Buy and Sell Stock with Cooldown

#Day_11

New
681. Next Closest Time

Stage II : 分类各个击破
day14-09/20-DFS+backtracking，基本可以无障碍做出来，但是缺乏优化，还有几道题有死角，待处理
DFS：
1. 78. Subsets
2. 90. Subsets II
3. 131. Palindrome Partitioning
4. 130. Surrounded Regions
5. 79. Word Search
6. 51. N-Queens
7. 52. N-Queens II
8. 17. Letter Combinations of a Phone Number
9. 22. Generate Parentheses
10. 40. Combination Sum II
11. 39. Combination Sum
12. 47. Permutations II
13. 46. Permutations
14. 77. Combinations

# Day 1
494. Target Sum
282. Expression Add Operators

Day_19 (9/19)

Insert node in a BST tree
Connecting graph

# Day_19
Array
Find the Duplicate Number
Game of Life