纽约在职刷题

628. Maximum Product of Three Numbers. Linear Scan写出来的还没有用sorted跑出来的快，LOL

63. Unique Paths II. Dynamic Programming加一个条件检查。Dynamic Programming要检查初始的解是不是完全对的。

91. Decode Ways. 跟63一样注意初始解设定。

204. Count Primes. Deletion (composite numbers)  based algorithm.

142. Linked List Cycle II. Fast slow pointers. Check的条件是fast and fast.next.

207. Course Schedule. Topological Sort, In_degree based. Graph Construction. Queue.

一不小心又10天没有刷题了。

1109. Corporate Flight Booking. 这个mark running sum变化的index，解法很聪明的感觉。

复习
Dynamic Programming, Recursion, Memoization and Backtracking.

17. Letter Combinations of a Phone Number


补充内容 (2019-8-7 01:37):
139. Word Break. Backtracking/Dynamic Programming 大概两条思路，top down, bottom up/ extension. 第二类一般也能用BFS解。

补充内容 (2019-8-20 01:06):
416. Partition Equal Subset Sum. Knapsack problem. Bottom up dynamic programming. 状态转换因为都是正数，可以从大和往小和去update，节省空间

补充内容 (2019-8-20 01:50):
96. Unique Binary Search Tree. 有点傅里叶变换convolution形式的Dynamic Programming

补充内容 (2019-8-20 03:39):
152. Maximum Product Subarray. 类似于Maximum Sum Subarray, Kadane Method. 保持两个DP状态。DP记录ending at index i.

55. Jump Game. 自己用BFS写了一下，一眼望去DP的题目最优解是Linear的greedy。

补充内容 (2019-8-22 22:56):
739. Daily Temperatures. 用Stack记录Monotonic Sequence，从前往后和从后往前扫一遍都可以。

补充内容 (2019-8-22 23:33):
287. Find the Duplicate Number. 传说中Knuth花了24个小时才解决了的问题，我等就只能背答案了。fast and slow pointers for cycle detection in linked list. Integer array to linked list function map.

补充内容 (2019-8-22 23:50):
102. Binary Tree Level Order Traverse. BFS两种实现，要记录level来organize output.

补充内容 (2019-8-23 01:10):
337. House Robber III. Dynamic programming在树上实现成了DFS。有两个递归状态要记录中间值。不需要Memoization因为解决了overlapping subproblem.

LeetCode Top Interview Questions:

237. Delete a Node in a Linked List. Change value hack

217. Contains Duplicate. Hash table. Pythonic lengths compare.

108. Convert Sorted Array to Binary Search Tree. Recursion

171. Excel Sheet Column Number. Conversion.