Skip to content

Latest commit

 

History

History
141 lines (112 loc) · 5.32 KB

arts-0002.md

File metadata and controls

141 lines (112 loc) · 5.32 KB

1.Algorithm

[1]  Two Sum

Easy    array    hash-table

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

Example:

Given nums = [2, 7, 11, 15], target = 9,

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

解答 本题可以采用常规的方法和基于 hashtab 的方式进行处理(题目描述中已经定义不存在重复的数据)

(1).常规解法, 2 层循环，时间复杂度 O(n*n)
result := make([]int, 2)
for i := 0; i < len(nums); i++ {
	var item = nums[i]
	var nextItem = target - item
	for j := i + 1; j < len(nums); j++ {
		if nextItem == nums[j] {
			result[0] = i
			result[1] = j
			break
		}
	}
}
	return result
(2).基于 Hash，算术运算, 改成 1 层循环，时间复杂度 O(n)， 用空间换时间的思路
vMap := make(map[int]int)
for index, item := range nums {
  if _, ok := vMap[target-item]; ok {
    return []int{vMap[target-item], index}
  }
  vMap[item] = index
}
return []int{}

2.Review

本周阅读的一遍文章是：如何给 6 岁的小孩解释计算机 Explaining Programming to 6 Years Old Kids

  • Keep them engaged by asking questions and drawing
  • Build upon what they already know

tips & tricks

  • It was more fun than I expected! I treated this seriously and I was well prepared, and it paid off.
  • Drawing pictures is the right way to go.
  • Be prepared for repeating things over and over again.
  • Some kids will get bored no matter what you do. Their attention span is simply too short.
  • Write carefully
  • During the presentation I understood that there is no point in correcting them
  • The presentation took me ~25 minutes.

3.Tip

本周在项目实施过程中遇到前端校验cookie的一个问题，开始一直没太注意，后来反复出现了几次才定位这个问题。实际情况是：

  • 应用A和应用B是同一个二级域名下的2个不同三级级域名，比如: a.xx.com, b.xx.com
  • A应用写的cookie绑定的path为a.xx.com，但是B应用绑定的path为*.bb.com， 同时都设置了HttpOnly
  • 当登录B应用后，cookie写入浏览器。A应用再次登录时，B应用登录成功后将cookie写入浏览器后，但是后续所有请求带的token去后端校验都会失效，认为是非法token

3.1分析问题：

对《cookie之困》的一些总结与思考

其中有3部分知识点

  • Cookie基础：同源策略(SOP)
* Web SOP:[protocol, domain, port]
 http://www.bank.com
 http://www.bank.com:8080
 https://www.bank.com
 总结：非同源（受SOP隔离保护）

* Cookie SOP:[domain, path]
-- 仅以domain/path作为同源限制
-- 不区分端口
-- 不区分HTTP/HTTPS
  • Cookie基础：Domain向上通配
* 在对Cooke读写时，以“通配”的方式判断Domain是否有效
-- 写入：
  当页面为http://www.bank.com时
  Set-Cookie: user1=aaa; domain=.bank.com; path=/;     [有效]
  Set-Cookie: user2=bbb; domain=www.bank.com; path=/;  [有效]
  Set-Cookie: user3=ccc; domain=.www.bank.com; path=/; [有效]
  Set-Cookie: user4=ddd; domain=other.bank.com; path=/;[无效]
-- 读取：
  访问http://www.bank.com
    Cookie: user1=aaa; user2=bbb; user3=ccc;
  访问http://user.bank.com
    Cooke: user1=aaa;
  • Cookie基础：Path向下通配
  Set-Cookie: session=bob; domain=.bank.com; path=/;
  Set-Cookie: cart=books; domain=.bank.com; path=/buy/;

  http://bank.com/       => Cookie: session=bob
  http://bank.com/buy/   => Cookie: session=bob; cart=books

4.Share

现役司的技术转型之路

这篇文章对公司的现状及自理提供了一个真实的案例场景，具有很强的参考价值。需要再次细读

我的学习方法论

System Design 记录作者有关架构面试的一些知识整理文章，非常有参考价值。 比如第一篇Deep Dive Into System Design 面试者系统架构方面需要考察的点：

  • Examine relevancy: Does the candidate have relevant working experience? Especially for critical problems in my projects.
  • Examine potential: How deep the candidate understand about the concepts in our domains, and also the painpoints.
  • Examine skills: Is he/she able to bring up a qualified architecture design with given constraints by discussing together.

Resources To Learn System Design: