在职刷题打卡，目标工作日一天2题，周末一天5题

#Day_17

完成 * 2:
LC 93. Restore IP Addresses
LC 445. Add Two Numbers II

今天确实没有增加题，把昨天的题用另一种方法写了一遍
然后学习了一下Remove Invalid Parentheses的思路，准备明天写出来
其他花些时间做了一下复盘，检视一下现在的刷题效果和速度，看了些帖子，结论是大致方向正确，有些方面可以做一些调整。比如一题不必花过多的时间，30分钟完全没思路or觉得可能可行但是写不出来（其实是思路有问题）就看系统的solution，以及简单和medium题写的时候开始解释，养成一边写代码一边说话的习惯（变成话痨）。

#Day_18

今天有点忙，本来打算随便提交两道简单题，但有道题实在太侮辱智商了于是又多做了一道:
LC 13. Roman to Integer
LC 344. Reverse String
LC 283. Move Zeroes

I slept through the DAY 5..Orz

Day 6, DP
1. Decode Ways, f[n] = f[n - 1] + f[n - 2], to check whether one digit num or two digit num could be decoded to letter
2. Palindrome Partitioning II, f[n] = min(i = 0...n-1) { f[i] } + 1 || 0, calculate boolean[][] isPalin to record whether a certain substring in the string is a palindrome
3. Decode Ways II, f[n] = f[n - 1] * singleDigitWays + f[n - 2] * twoDigitWays, pay extra attention to how to calculate twoDigitWays, esp when for "*1"
4. Backpack, f[n] is the max value that a backpack with weight n could reach

生病了还去camping，状态不行啦……鸽两天

#Day_19

搬家搬完凌晨四点。只能提交两道ez了：
LC 771. Jewels and Stones
LC 121. Best Time to Buy and Sell Stock

#Day_20

完成 * 2:
LC 46. Permutations
LC 412. Fizz Buzz

remove Invalid Parentheses 暴力backtracking，对每一位有两种选择，要或者不要，要的话left+1，进入下一层。right的话下一层之前判断两者是否相等，相等就不用下一层了，这样剪个枝。
Linked List Cycle 弗洛伊德判圈法

Day 9
Busy w/ Other stuff for Day 7 & 8...Orz

1. Maximum Product Subarray, dp, need to understand the problem
2. Backpack II, dp, whether to put the ith item to the backpack.

Need to do more problems and really start transit to prepare mode!!

#Day_21

Finished * 2:
LC 692. Top K Frequent Words
LC 11. Container With Most Water