Mock Interview

Question1: https://leetcode.com/problems/shortest-unsorted-continuous-subarray/description/
Question 2:
Imagine we are a software development company and we manage our dev process using an issue tracking tool. Each issue has an ID and also a list of IDs of issues which block it (Blockers or parents). As a result we have 1 or multiple unidirectional graphs because there could have several root issues.

At some point in time someone added an issue A as a Blocker of issue B. But because A was already blocked by the descendants of the current issue B (descendants of B are the issues that are transitively blocked by B), this created a circular dependency. After this our UI issue tracking tool (Taskflow) stopped showing issues correctly. Our task is to find out all circular dependency loops.

The input is a 2D boolean array of blockers assignments. The row number is the issue ID. The column number is Blocker issue ID. So entry (i, j) is True means that issue i is blocked by issue j.
Example input:
Where for (i,j)
(0,0)=False | (0,1)=False | (0,2)=True
(1,0)=True | (1,1)=False | (1,2)=False
(2,0)=False | (2,1)=True | (2,2)=False

The output is a list of dependency cycles. The order inside one cycle doesn't matter.
Example:
[
[0, 2, 1] (as well can be 2,1,0 or 1,0,2)
]

Coding 1

You're given a log stream of a chat application. Every log entry has the following fields:

timestamp: long - the number of seconds that have elapsed since 1970-01-01.
sender: str - username of the sender
receiver: str - username of the receiver
message_text: str - the message payload
We want to implement a log stream processor which supports two methods:

RegisterEvent(timestamp, sender_username, receiver_username, message_text) - registers the event that the message have been sent
GetMostActiveUser() - Returns the user with the largest number of active conversations. We count any amount of messages exchanged between two unique users as a single conversation.
Examples:

RegisterEvent(0, "A", "B", "Hi!")
GetMostActiveUser() -> "A" or "B"
// Both users have a single conversation.
RegisterEvent(10, "A", "C", "Hi!")
RegisterEvent(15, "C", "A", "Hi, there!")
GetMostActiveUser() -> "A"

Coding 2

EExample Messages Received, with Timestamps:

10 solar panel activated
11 low battery warning
12 tire one: low air pressure
13 solar panel activated
14 low battery warning
21 solar panel activated
35 solar panel activated

Example Messages Shown to User:

10 solar panel activated
11 low battery warning
12 tire one: low air pressure
21 solar panel activated
35 solar panel activated

//sorted timestamp
//stream of data, decide best way to represent incoming data
//only message in output, order in output

//10 secs, requirement, within 10 de-duplciate, after that show the message
//Set messagesSet
//List messagesList

//
Map<String, Integer> messageToLastTimestamp = new HashMap<>();
void recieveAndSendMessage(long timestamp, String message){
if(!messageToLastTimestamp.containsKey(message) || messageToLastTimestamp.get(message) < timestamp - 10) {
messageToLastTimestamp.output(message, timestamp);
sendMessgae(message);
return;
}
return;
}

Example Messages Received:

10 solar panel activated
11 low battery warning
12 tire one: low air pressure
14 low battery warning
21 solar panel activated => 10 solar panel ...
35 alkndfslsdnf => 12
<no more messages received for another 11 seconds>

Coding 3

//Maps, 1) roads one way 2) city name is unique 3) no cycles
//design class, starting from a given city, all the rechable cities from given city
//cities = [a, b, c, d], edges: [[a,b]...]
//input: "a"
//output: [b,c,d]
//scale: big