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[实习] 实习面经和offer

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bmwx3 发表于 2014-2-12 09:09:18 | 显示全部楼层 |阅读模式

2014(1-3月)-[11]Stat/Biostat博士+fresh grad 无实习/全职 - 网上海投| 码农类实习@

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上次问过大家offer选择的事儿,这两offer都不错,最后决定去yahoo!. 我以前没有实习经验,统计系博士在读。找工作方向机器学习。. from: 1point3acres.com/bbs
. 涓浜-涓夊垎-鍦帮紝鐙鍙戝竷
Yahoo! lab: $7500一个月 + 一次性补助 $4500 + 机票
Amazon: $7400一个月 + 一次性补助 $7500 + 机票
Google 过了第一轮两个面试,在host match阶段两周了也没经理挑我,因为另两个offer需要答复,等不了了就withdraw了。

1. Yahoo!: 两轮面试都是国人,非常友好。没有考我什么难的题目,就是聊了聊实习要做的项目,可能是因为要做的东西跟我背景很相近。第二轮经理问了一些linear regression的问题,都很基本。之后没几天就给了offer。要是国人面试官都这么帮忙该多好啊~. 鍥磋鎴戜滑@1point 3 acres


2. Amazon: 两轮面试,前后隔了20天,第二轮面完后两三天给了offer。
第一轮是欧洲人,研究方向large scale machine learning.
.鐣欏璁哄潧-涓浜-涓夊垎鍦
Q1: Big data (billions), can not fit into one machine, how to fit linear regression model?
答曰 online learning, Stochastic gradient descent.

Q2: In Stochastic gradient descent, what's the moving direction of parameter space?
答曰 negative of derivative of error function。

. from: 1point3acres.com/bbs Q3: How does the derivative of error function change if we increase the training sample? i.e. difference between stochastic gradient descent and batch gradient  descent?
只知道跟estimator是否stable相关,不知道具体的,面试官提醒了半天,最后放弃了。

Q4: Data Structure. How to find the median of a sequence? Complexity? How to improve?

Q5: We know decision tree is unstable for regression. How to improve?
答曰 bagging.

Q6: How to parallel it?
答曰 Run each bootstrap sample in one machine, then combine all estimator.

Q7: If the sample size is too large s.t. one bootstrap sample can not fit in one machine?
答曰 parallel based on features.

第二轮美国人,Machine learning scientist。问了很多我的一个project,跟他想做的一个东西很相关。
.1point3acres缃
Q1: Binary Gene data, two classes, n<<p. How to figure out the informative gene for classification?
我正在做的一个project就是这个,聊了很多。

Q2: Kmeans only find local optimization in general. If dimension equals one, we can find global optimal. How to efficiently find the global optimal in 1d k-means? what's complexity?
这题我给的算法复杂度不是很好,当k=2时候,最多只有n-1种可能,遍历就好。我的算法只是polynomial in n, exponential in k. 他说就这样吧,得留点时间问下一题就没接着问。之后网上查到有用dynamic programming的。

Q3: To store data with "Keyname" and "value", which data struture to use? What's the advantage and disadvantage of each data structure?
我只说了我知道的data structure,他期望的答案是hash table, 我说我不了解,他说这个应用非常广。

Q4: Which operating systen do you use? programming language?
他们主要用windows. 用R,python,java.


3. Google: software engineer intern。 我觉得答得很烂,很多题目都不知道什么意思,也不知道咋的就过了,面试分数可能刚好过线吧。
第一轮印度面试官。
1. What happens to Ram, memory and heap when you call a function f(x)=x+1?
答曰: do not know. 我就是一个学统计的。。。

2. Detect if there is a cycle in directed graph. If no cycle, sort this graph in order in linear time. Complexity?. more info on 1point3acres.com
答曰: Use DFS. for the second one, do not know.

3. In linear regression, what's the assumption of model? Why use L2 norm in MSE?
答曰: error is normal, constant variance and independent. L2 norm is because error only has second moment.

4. What's the difference between generative model and discriminative model?

第二轮韩国女面试官,纯软件工程师,一点machine learning 背景都没有。

1. Coding problem: check if a binary tree is balanced or not. what's the complexity?
Me: 在google docs 上写程序。。。
. From 1point 3acres bbs
2. Design a user database such that when a user logins in , add it; when a user logs out, remove it.
Me: Use Stack, Queue. when insert, O(1); when delete, complecity O(n).
面试官: Can you improve?. 1point 3acres 璁哄潧
Me: No.
面试官: How about hash table? Can you code how to insert element using hash table?
Me: Sorry, I do not know. 看来hash table确实要掌握。。。


鏉ユ簮涓浜.涓夊垎鍦拌鍧.
.1point3acres缃


-google 1point3acres









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数字媒体技术 发表于 2014-2-12 23:04:26 | 显示全部楼层
每次看地里报OFFER就深深感觉到非CS专业的苦逼。。。这实习工资比很多fulltime都多,我一朋友在凯悦做管培$38000/y....
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lovegrows 发表于 2014-2-13 00:34:44 | 显示全部楼层
恭喜恭喜!我也拿到了Yahoo! Lab的实习,不过只是口头offer,能留你个联系方式咨询一下么?
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Lolipop 发表于 2016-4-6 20:57:45 | 显示全部楼层
this is great!
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