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Day
1898
DS Interview Question
What’s the differences between the poission distribution and normal distribution?
LeetCode Question
Write a query in SQL to count the number available rooms.
Sample table: room
roomnumber | roomtype | blockfloor | blockcode | unavailable
-----------+------------+------------+-----------+-------------
101 | Single | 1 | 1 | f
102 | Single | 1 | 1 | f
103 | Single | 1 | 1 | f
111 | Single | 1 | 2 | f
112 | Single | 1 | 2 | t
113 | Single | 1 | 2 | f
121 | Single | 1 | 3 | f
122 | Single | 1 | 3 | f
123 | Single | 1 | 3 | f
201 | Single | 2 | 1 | t
202 | Single | 2 | 1 | f
203 | Single | 2 | 1 | f
211 | Single | 2 | 2 | f
212 | Single | 2 | 2 | f
213 | Single | 2 | 2 | t
221 | Single | 2 | 3 | f
222 | Single | 2 | 3 | f
223 | Single | 2 | 3 | f
301 | Single | 3 | 1 | f
302 | Single | 3 | 1 | t
303 | Single | 3 | 1 | f
311 | Single | 3 | 2 | f
312 | Single | 3 | 2 | f
313 | Single | 3 | 2 | f
321 | Single | 3 | 3 | t
322 | Single | 3 | 3 | f
323 | Single | 3 | 3 | f
401 | Single | 4 | 1 | f
402 | Single | 4 | 1 | t
403 | Single | 4 | 1 | f
411 | Single | 4 | 2 | f
412 | Single | 4 | 2 | f
413 | Single | 4 | 2 | f
421 | Single | 4 | 3 | t
422 | Single | 4 | 3 | f
423 | Single | 4 | 3 | f
BA Interview Question
Rotate Array
Deion:
Rotate an array of n elements to the right by k steps.
For example, with n = 7 and k = 3, the array [1,2,3,4,5,6,7] is rotated to [5,6,7,1,2,3,4]. Could you do it in-place with O(1) extra space?
Input: [1,2,3,4,5,6,7] 3
Output: [5,6,7,1,2,3,4]
Day
1897
答案揭晓
DS Interview Question & Answer
Define: quality assurance, six sigma.
Quality assurance:
- A way of preventing mistakes or defects in manufacturing products or when delivering services to customers
- In a machine learning context: anomaly detection
Six sigma:
- Set of techniques and tools for process improvement
- 99.99966% of products are defect-free products (3.4 per 1 million)
- 6 standard deviation from the process mean
LeetCode Question & Answer
Write a query in SQL to find the floor and block where the room number 212 belongs to.
Sample table: room
roomnumber | roomtype | blockfloor | blockcode | unavailable
---------------------+---------------+-----------------+----------------+-------------
101 | Single |1 | 1 | f
102 | Single |1 | 1 | f
103 | Single |1 | 1 | f
111 | Single |1 |2 | f
112 | Single |1 |2 | t
113 | Single |1 |2 | f
121 | Single |1 |3 | f
122 | Single |1 |3 | f
123 | Single |1 |3 | f
201 | Single |2 |1 | t
202 | Single |2 |1 | f
203 | Single |2 |1 | f
211 | Single |2 |2 | f
212 | Single |2 |2 | f
213 | Single |2 |2 | t
221 | Single | 2 | 3 | f
222 | Single | 2 | 3 | f
223 | Single | 2 | 3 | f
301 | Single | 3 | 1 | f
302 | Single | 3 | 1 | t
303 | Single |3 |1 | f
311 | Single | 3 |2 | f
312 | Single | 3 |2 | f
313 | Single |3 |2 | f
321 | Single |3 |3 | t
322 | Single |3 |3 | f
323 | Single |3 | 3 | f
401 | Single |4 |1 | f
402 | Single |4 |1 | t
403 | Single |4 |1 | f
411 | Single | 4 |2 | f
412 | Single |4 |2 | f
413 | Single |4 |2 | f
421 | Single |4 |3 | t
422 | Single |4 |3 | f
423 | Single |4 |3 | f
Answer:
SELECT blockfloor AS "Floor",
blockcode AS "Block"
FROM room
WHERE roomnumber=212;
Output:
Floor | Block
-------+-------
2 | 2
(1 row)
BA Interview Question & Answer
Combine Two Tables
Deion:
Write a SQL query for a report that provides the following information for each person in the Person table, regardless if there is an address for each of those people:
FirstName, LastName, City, State
Input:
Table: Person
+-------------+---------+
| Column Name | Type |
+-------------+---------+
| PersonId | int |
| FirstName | varchar |
| LastName | varchar |
+-------------+---------+
PersonId is the primary key column for this table.
Table: Address
+-------------+---------+
| Column Name | Type |
+-------------+---------+
| AddressId | int |
| PersonId | int |
| City | varchar |
| State | varchar |
+-------------+---------+
AddressId is the primary key column for this table.
Solution:因为每个人不管地址存不存在都要在新表中，所以用person表左外连接address表
Code:
SELECT a.FirstName, a.LastName, b.City, b.State
FROM Person a
LEFT OUTER JOIN Address b
on a.PersonId = b.PersonId;返回搜狐，查看更多