缺大米的请参加这个刷题/Mock interview活动

6.23 day24
139 medium trie + memorization 不memo的话会TLE
140 hard trie + memo 这题其实可以不用trie，直接用startsWith()，bottleneck在于memo
143 medium 指针转换题就几个基本模块来回组合，想复杂了反而做不出来

打卡第五天，6题

6/23/20

994        Rotting Oranges
BFS, 类似另一道题Zombie in Matrix

981        Time Based Key-Value Store
Hash map + Binary Search
题目里说明里set调用时timestamp单调递增，set直接append，get用binary search

1060        Missing Element in Sorted Array
Binary search, 注意边界条件

6.23 打卡6道DP+1道堆

第14天。

Day 15
昨天晚上又做了个mock interview，总结一下：
1. 在听完问题后应该花3分钟左右问问题和考虑edge cases，但是超过5分钟就没有必要了，毕竟也要为做题留充足的时间。
2. Interviewer可能会问到一些data structure知识点，可以简单复习一下。比如说我昨天被问到adjacency list和adjacency matrix。
3. 想问题的时候无论想的对不对，都应该把心里正在想的东西说出来。尽量不要超过一两分钟不说话吧。
然后我这几天还得继续提高解比较简单题的速度，和分析时间复杂度的速度。

坚持12天了。今天做了3道BFS的题目， 就是重新熟练一下BFS的解题方法和如何用Queue实现BFS。

20200622:
3: 0137, 1080, 1245, 1273, 1339, 1448, 1475
4: 0979
5:

First day to brush leetcode to solve 6 problems in a day.
Tips:
1. When leetcode responds too slow, do NOT wait for the submission/running result; Go for another problem;
2. When counting and decreasing ints, check if we can decrease more than 1 in one operation;  E.g., LC1296.
3. When increase/decrease a batch of elements, try to achieve time O(1) instead of O(n). E.g., LC1381.

06.22 刷题第十一天 打卡第十一天
刷题12道

1-1281. Subtract the Product and Sum of Digits of an Integer
Mindset：
two variables and a for loop so we can get the answer

2-724. Find Pivot Index
Mindset: Prefix sum
then when we update the i, leftsum were supposed to updated too!

3-1304. Find N Unique Integers Sum up to Zero
Mindset: Handle this question in terms of even or an odd number
quiet straight forward.

4-217. Contain duplicates I
Mindset:
use HashSet then linear scan

5-219. Contain duplicates II
Mindset:
Same, use HashSet then linear scan

6-220. Contain duplicates III
Mindset:
Bucket sort

7-665. Non-decreasing Array
Mindset:
Greedy
there are two approaches to changing this element
change the current one or change the former one(i - 1)

Also, I need to use an int variable to save change times

8-Longest square surrounded by one

2*2D - matrix DP
find the longest edge and then check two corners(leftBottom and rightTop)

9-longest common string
find two common strings by using
A-2D matrix DP
use start int variable and end variable

10-longest common subsequence
similar to 9

11-Leetcode 986 interval List Intersection && 12- Follow up
set up new class

class Intersect{
   int start;
   int end;
}

return a list of Intersect

12-Follow up
check each intersect
to see if any intersect we can schedule a meeting with a manager which at least last for x mins

楼楼大大，最近11天都没有拿到大米，求米求米！！