每日一练 | Data Scientist & Business Analyst & Leetcode 面试题 213

大数据应用 · 公众号 · 大数据 · 2017-10-14 09:43

正文

从6月15日起，数据应用学院将与你一起温习数据科学（DS）和商业分析（BA）领域常见的面试问题。从10月4号起，每天再为大家分享一道Leetcode算法题。

希望积极寻求相关领域工作的你每天关注我们的问题并且与我们一起思考，我们将会在第二天给出答案。

Day 113

DS Interview Questions

Write the code to sort an array in NumPy by the nth column

BA Interview Questions

R programming: what is the differences between the values of “coef()” and “（exp）coef” when you have a regression model?

Leetcode Questions

Remove Duplicates from Sorted Array II

Description:

Follow up for "Romove Duplicates"

What if duplicates are allowed at most twice?

Input: [1,1,2,2,2,3,3,3]

Output: [1,1,2,2,3,3]

欲知答案如何？请见下期分解！

Day 112 答案揭晓

DS Interview Questions

How can you check if a data set or time series is Random?

To check whether a dataset is random or not, use the lag plot. If the lag plot for the given dataset does not show any structure then it is random.

BA Interview Questions

R Programming: explain the usage of which() function in R language and name an example of that function

which() function determines the position of elements in a logical vector that are TRUE. for example,

mydata = data.frame(v1=c(2,4,12,3,6))

which(mydata$v1 == max(mydata$v1))

It returns 3 as 12 is the maximum value and it is at 3rd row in the variable x=v1

Leetcode Questions

Remove Duplicates from Sorted List

Description:

Given a sorted linked list, delete all duplicates such that each element appear only once

Input: 1 → 1 → 2

Output: 1 → 2

Tips: 基础的链表去重题目，需要用到dummy node来简化特殊情况，省去很多条件判断，每次遍历一个node,需要注意指针的赋值

Code:

时间复杂度：O(n)

空间复杂度：O(1)

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