[第二期活动] 在职刷题打卡，目标工作日一天2题，周末一天5题

Day_4 (8/17)

Inorder Successor in BST
Binary Tree Upside Down
Word Break
Maximum Depth of Binary Tree
Validate Binary Search Tree

#Day_17

Finished * 2
539. Minimum Time Difference
199. Binary Tree Right Side View

Day 14
301 remove invalid parentheses, dfs,  process section by section, be careful the case of removing ( is similar but not exactly the same with the removal of )
207 course schedule, bfs and attempt to solve w/ dfs, follow up on 210 course schedule ii w/ bfs
630 course schedule iii, greedy + heap
269 alien dictionary, topological sort, on the saumption that the letter could be ordered will be put in the order of its appearance
329 longest increasing path in a matrix, dfs + memoization (bottom up)
317 shortest distance from all buildings, bfs (level) + need to ensure the point you picked is land and could reach all houses (num_houses_reached)
896 mononic array, O(n), simple problem usually could be solved in a clean way

Day 2

4. Median of Two Sorted Arrays - Classic binary search problem. Needs to think about the edge cases. Needs to revisit in the future.
45. Jump Game II - Intuitive solution is DP, but O(n**2) is a bit too slow. Interesting optimization via greedy to O(n).
438. Find All Anagrams in a String - Classic sliding window
80. Remove Duplicates from Sorted Array II - Very similar to Remove Duplicates from Sorted Array I
277. Find the Celebrity - Interesting O(n) 2-pass
41. First Missing Positive - Similar to counting sort. Saving space by encoding if a positive integer is seen into the array itself.
299. Bulls and Cows - Easy using hash map
134. Gas Station - Interesting 1 pass O(n) solution
119. Pascal's Triangle II

day 15
完成5题
Insert into a Binary Search Tree
Range Sum of BST
Closest Binary Search Tree Value II
Closest Binary Search Tree Value
Kth Smallest Element in a BST

bixingxie 发表于 2019-8-19 11:43
Day 2

4. Median of Two Sorted Arrays - Classic binary search problem. Needs to think about the e ...

哇，一天八九题这个速度可以啊

Day_5 (8/18)

Word Squares
N-Queen
N-Queen II
Letter combination of a phone number
Find position Unique Character

Facebook -  Remove Invalid Parentheses

总结心得在此
https://hackmd.io/MfyiJdjPR5OkNB15yE3PYA

#Day_6

986. interval list intersections
125. valid palindrome
227. basic calculator ii

#Day_18

Finished * 4
Employee Free Time
Find First and Last Position of Element in Sorted Array
Pour Water
Friend Circles