专栏名称: 大数据应用

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每日一练 | Data Scientist & Business Analyst & Leetcode 面试题 726

大数据应用 · 公众号 · 大数据 · 2019-10-24 08:46

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点击上方蓝字会变美

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每

日

一

练

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Oct.

Data Application Lab 自2017年6月15日起，每天和你分享讨论一道数据科学(DS)和商业分析(BA) 领域常见的面试问题。

自2017年10月4日起，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

626

DS Interview Question

What are methods to make a predictive model robust to outliers?

BA Interview Question

Duplicate Emails

Write a SQL query to find all duplicate emails in a table named Person.

+----+---------+
| Id | Email |
+----+---------+
| 1 | [email protected] |
| 2 | [email protected] |
| 3 | [email protected] |
+----+---------+

For example, your query should return the following for the above table:

+---------+
| Email |
+---------+
| [email protected] |
+---------+

Note: All emails are in lowercase.

LeetCode Question

Permutation Sequence

Description:

The set [1,2,3,…,n] contains a total of n! unique permutations.

By listing and labeling all of the permutations in order,

We get the following sequence (ie, for n = 3):

"123"

"132"

"213"

"231"

"312"

"321"

Given n and k, return the kth permutation sequence.

Input: 3, 2

Output: 132

Assumptions:

Given n will be between 1 and 9 inclusive.

Day

625

答案揭晓

DS Interview Question & Answer

Tell me some majors issues needed to be considered in supervised machine learning?

Bias-variance tradeoff
Function complexity and amount of training data
Dimensionality of the input space
Noise in the output values
Input data problems such as Heterogeneity of the data, Redundancy in the data and Presence of interactions and non-linearities.

Reference:https://en.wikipedia.org/wiki/Supervised_learning

BA Interview Question & Answer

Employees Earning More Than Their Managers

The Employee table holds all employees including their managers. Every employee has an Id, and there is also a column for the manager Id.

+----+---------+
| Id | Email |
+----+---------+
| 1 | [email protected] |
| 2 | [email protected] |
| 3 | [email protected] |
+----+---------+

Given the Employee table, write a SQL query that finds out employees who earn more than their managers. For the above table, Joe is the only employee who earns more than his manager.

+---------+
| Email |
+---------+
| [email protected] |
+---------+

Answer:

# Join

select e1.name from Employee e1
join Employee e2 on e1.ManagerId=e2.Id
where e1.Salary>e2.Salary;

# where
select e1.name from Employee e1,Employee e2
where e1.ManagerId=e2.Id
and e1.Salary>e2.Salary;

Reference:

https://leetcode.com/problems/employees-earning-more-than-their-managers/solution/s/solution/