刷题记录帖

周五太忙了

541. Reverse String II
1260. Shift 2D Grid
similar question.

303. Range Sum Query - Immutable
some thing to pay attention here.


62. Unique Paths
follow up: what if you have to pass a point? count the number.
what if you have to pass a line.
tsp trverse man problem
307. Range Sum Query - Mutable

boolean to record the status of the one
[true false, true, false]

bit manipulate

binary index tree


suan fa jing sai rumenjingdian
https://github.com/dzsky/f***sky ... 7%89%88%EF%BC%89%20(%E7%AE%97%E6%B3%95%E8%89%BA%E6%9C%AF%E4%B8%8E%E4%BF%A1%E6%81%AF%E5%AD%A6%E7%AB%9E%E8%B5%9B).pdf
contest
three of them

周日休息

65. Valid Number
https://www.geeksforgeeks.org/dy ... -polymorphism-java/
https://leetcode.com/problems/ro ... xplanation-and-6ms-(99)-Solution

https://gist.github.com/vasanthk/485d1c25737e8e72759f
https://blog.imgur.com/2013/06/0 ... r-technology-stack/
https://archive.org/details/ucbe ... 2QzAV-R7NMA1ZkaiR2y

100. Same Tree
use iterative
https://www.w3schools.com/java/java_break.asp
https://www.freecodecamp.org/new ... mmies-5e048933b82b/
https://interviewing.io/?urc=DMCa
--！！hashmap的实现原理
Computer Science 101

cracking the coding interview
princeton data structure
hashcode basic

code style guide
https://google.github.io/styleguide/javaguide.html

How big is the size of the input?
How big is the range of values?
What kind of values are there? Are there negative numbers? Floating points? Will there be empty inputs?
Are there duplicates within the input?
What are some extreme cases of the input?
How is the input stored? If you are given a dictionary of words, is it a list of strings or a trie?

This is usually the hardest part of the interview. In general, look for repeated work and try to optimize them by potentially caching the calculated result somewhere. Reference it later, rather than computing it all over again. I provide some tips on tackling topic-specific questions in detail below.

How to write test plan?
what is testable code?
what resource i can find for learn testing.

20. Valid Parentheses
Stack:
possible corner case:
when use pop(), there might be a chance that stack is empty.
22. Generate Parentheses
brute force

def generateParenthesis(self, N):
    if N == 0: return ['']
    ans = []
    for c in xrange(N):
        for left in self.generateParenthesis(c):
            for right in self.generateParenthesis(N-1-c):
                ans.append('({}){}'.format(left, right))
    return ans

这是什么？

Approach 2: Backtracking
good!
How to analyse time complexity?

study more.
hao ti.
Approach 3: Closure Number
https://leetcode.com/problems/ge ... An-iterative-method

94. Binary Tree Inorder Traversal
144. Binary Tree Preorder Traversal
145. Binary Tree Postorder Traversal
102. Binary Tree Level Order Traversal
100. Same Tree
how can you control the number pop out in queue when do travel order traversal?


The operation of ArrayList:
102. Binary Tree Level Order Traversal
Iterative way.
https://www.geeksforgeeks.org/linked-list-in-java/

20. Valid Parentheses
Stack:
possible corner case:
when use pop(), there might be a chance that stack is empty.
22. Generate Parentheses
brute force

def generateParenthesis(self, N):
    if N == 0: return ['']
    ans = []
    for c in xrange(N):
        for left in self.generateParenthesis(c):
            for right in self.generateParenthesis(N-1-c):
                ans.append('({}){}'.format(left, right))
    return ans

这是什么？

Approach 2: Backtracking
good!
How to analyse time complexity?

study more.
hao ti.
Approach 3: Closure Number
https://leetcode.com/problems/ge ... An-iterative-method

20. Valid Parentheses
Stack:
possible corner case:
when use pop(), there might be a chance that stack is empty.
22. Generate Parentheses
brute force

这是什么？

Approach 2: Backtracking
good!
How to analyse time complexity?

study more.
hao ti.
Approach 3: Closure Number
https://leetcode.com/problems/ge ... An-iterative-method


94. Binary Tree Inorder Traversal
144. Binary Tree Preorder Traversal
145. Binary Tree Postorder Traversal
102. Binary Tree Level Order Traversal
100. Same Tree
how can you control the number pop out in queue when do travel order traversal?


The operation of ArrayList:
102. Binary Tree Level Order Traversal
Iterative way.
https://www.geeksforgeeks.org/linked-list-in-java/