Linkedin Interview Part 3


reverse版本的nested integer
word distance

isomorphic str,没有followup。 想起地里之前有帖子说面试官说要twoway mapping, 说了两个map的解法,被吐槽空间复杂度太高。。。
search range.
http://www.1point3acres.com/bbs/thread-135904-1-1.html
1. Two sum III(leetcode)
2. bounded queue(consumer, producer )
还问了一些基本概念,virtual memeory, thread, process 区别等。

Phone interview2 :
1. merge two sorted inked list(从大到小)
2. 一个文件,有很多行string, 从里面提取所以valid的Ip address.
 (我当时用C++写的,有点麻烦,面试官最后给我看了,python代码,就两行,哎!)


Onsite Interview:
1. Talk with director.-
2. coding:
1. 给一个string, app[1,2].corp[3,4].com 要求返回:
app1.corp3.com, app2.corp3.com, app1.corp4.com, app2.corp4.com. 组合题变种。
2。给一个map, 里面是所有文件的dependency, 找出给定一个文件的所有dependency. 图的dfs遍历,
注意cycle的处理。没啥难的。

3. Lunch with Manager
4. Design: monitor systesm. 后半部分答的不好,和面试官不再一个频道上,估计挂了。
5. Technical communication.
6. coding: 1. print all factors of n(老题), 2.  Is valid BST(讨论了几种方法) (这轮也没啥难度)
http://www.1point3acres.com/bbs/thread-167542-1-1.html
1. implement singleton pattern,要注意constrctor是private
2. binary tree level order print,我用queue bfs做的,follow up是还有其他解法么,我说了可以用dfs
1. search a number in a 2-d array,行都是sorted的,每行第一个比前一行最后一个要大,转换成一维的array做 search就行了。面试官说size=row*column-1如果overflow怎么办,我说把int改成long就好了。

楼主遇到的是https://leetcode.com/problems/search-a-2d-matrix/,就按照一维数组做就好,坐标转换一下,就OK, O(1) Extra Space O(log(mn)) time

从右上角那个方法是对于https://leetcode.com/problems/search-a-2d-matrix-ii/
2. implement stack with pop(), push() and findmiddle() with O(1) time, 一开始我想用array做,面试官提醒resize的时候会有额外操作,就改用double linked list了。维护两个pointer,top和middle。follow up就是test case。
第二题用一个叫middle的pointer,findmiddle的时候就返回pointer,pop和push的时候要update middle的位置。
http://www.1point3acres.com/bbs/thread-166399-1-1.html
Blocking Bounded Queue
实现一个线程安全的put和get,这个之前看面经的时候练习过,不管怎么样写出来了 - - 
Follow up是 multi-put,这个没写出来,之后的30分钟都是在纠结Mutex和condition variable,因为不是非常理解C++多线程,所以应该会挂在这儿

http://www.1point3acres.com/bbs/thread-166389-1-1.html
然后问题是isomorphic string,先判断两个string,follow up是给一堆string, 按组输出isomorphic strings, 输出格式是List<List<String>>。小哥可能比较忙,中途离开了两次。。。
对,判断两个string的时候是true or false. Follow up是给一堆string,让分组输出

http://www.1point3acres.com/bbs/thread-145037-1-1.html
1. 两个华人。Design tiny URL 问了很多细节,最后居然问到了怎么配置memcache, 估计是不揭穿lz的画皮不甘心,不过相信他们是为了找我的亮点吧
2 两个华人
2.1 find range of a number in an array with possible duplicates, 我写的其实有bug, 但是小哥欣然放过,感谢。. from: 1point3acres.com/bbs 
2.2 find all palidrome string by deleting any letter from the given string. 这题比较难,我只做了dfs的bf解, 稍微加了个map trim branch一下。最优解在mitbbs有讨论,大家自己坐电梯去看
http://www.mitbbs.com/article/JobHunting/33053715_3.html-google 1point3acres
3. tech communication. 一华一印,被强烈bs. visit 1point3acres.com for more.
4. 一中一印 leetcode原题 most points on same line. 但是leetcode的斜率用float直接表示,这里被要求用更好方式表示,搞了个 横纵坐标的类,写gcd, 改hashcode, equals等吭哧半天。小中是一脸恨铁不成钢,不停提示我,恨不得上来帮我写,烙印是到处找茬,说你说lcd(lz没接受过正规cs教育, gcd说成lcd), 是不是还有led呢,blahblah。
http://www.1point3acres.com/bbs/thread-148200-1-1.html
1. Maximum Subarray,leetcode原题,基本的dp,应该很好写吧,也练过至少1次了。。然而lz我第一次真正意义上的技术电面,有点紧张,于是没有考虑数组为空的情况,被指出来,遂加上。。. 鐣欏鐢宠璁哄潧-涓€浜╀笁鍒嗗湴
2. Maximum product Subarray,leetcode原题,又是基本的dp,也应该很好写吧,也练过至少1次了。。然而。。。我一开始说思路的时候又没100%对上点,大哥遂说,算了算了,你先写吧。。。一开始写发现之前说的哪有漏洞了,改之。。。惊心胆战中好歹完成了。。

ml:
问的非常多且杂但是都不精,先从binary classifier是啥到举例,到你最喜欢哪个算法,我说logistic regression,于是开始问你介绍一下呀,我扯到了logistic function,具体他怎么问的我忘记了,只记得我一直在说指数函数、0、1、0.5边界值之类的。。。再后来他说怎么训练参数,就扯到了MLE,cost funtion,gradient descent,他问梯度下降是什么呀,学习率什么含义啊,还有regularization,问regularization是啥,我因此扯到了防止overfitting,他借此又问overfitting是啥,怎么解决,我说完后,他借由这几种解决方法拓展到了cross validation和pca(feature selection),于是我又扯扯扯到了pca的定义,他顺便问了一句pca怎么知道取几个component,这个问题我不确定,回答说这是个“pecentage problem"吧?如果想要80%或90%,就取到这个程度好了。。。英文表达真心捉急。。

我面了树的level order和zigzag遍历,ml方面是问了决策树,entropy之类的,还有l1, l2 regularisation,还有简历上的一点东西

http://www.1point3acres.com/bbs/thread-157908-1-1.html
我根本没准备system的东西结果问了一堆问题看来是要跪。。我记得有虚拟内存,事务,进程和线程的区别,进程通信线程通信,答得很差
然后一道design的题。。。。实现一个容器能够randomremove和正常加和删。。。我傻傻用了三个hashmap小哥一步一步引导我走向正确答案不过前面答得太差了估计没戏了
。。。。我真的以为一面是水leetcode的节奏结果就这么跪了。。。。

http://www.1point3acres.com/bbs/thread-159875-1-1.html
一共两轮。。。第一轮是三哥三姐,很和蔼,出的题也不难,一个是带字符的valid 括号,另一个是isomofic string,follow up 是3 个的情况。感觉他们都还蛮开心的,最后问问题,他们也很开心的回答了。。题目都是秒过,然后针对test case 解释了挺长时间。。英语渣~没办法。
第二轮 下午刚面完,一个是merge array,intersecion of two array, 果断秒过,小插曲:以为说的linkedlist,所以把merge linkedlist也写了一遍。。第二题是longest palindromic string (题目说的 subsequence),但是我想成substring了。。 不过事实证明面试官不在乎,你做出来了,并且表达清楚应该就没问题。

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