LC - Datadog

Question 1

Buffered file

Answer 1

You know it

Question 2

Logs and queries

Answer 2

Build query hash
Query hash to Id
Inverted index - word to query Id
For each word in log - for each query Id that contains it, add it to a list for the query Id
For each query Id, build a hash with all the words in the log and compare with original hash to Id dictionary

Question 3

Maximum tree path sum

Answer 3

Post order DFS

Question 4

Frequency of words

Answer 4

Dictionary

“”.join(c.lower() for c in s if c not in string.punctuation)

Question 5

File system

Answer 5

Basic recursion.

isDir()
findList()

Question 6

High performance filters

Answer 6

Build map from index to tags list
Build inverted index from tags to list of indexes
For each tag in the filter, add to the set of Ids that contain the tag.
Iterate through the set, check if the tag list contains all tags, and extend the result list