[From MITBBS] Facebook and Google Interview Questions

Facebook:
Phone:
Input: Given a matrix of 0, there are some areas populated with 1, 2, 3s.
Output: Map<int, numOfRegions>

Onsite:
Round 1: cultural, project deep dive, things that can be done better
Round 2: Calculator, implement a function to output the current display 
based on the inputs that is already typed.
Round 3: Word Ladder II in Leetcode
Round 4: Design facebook event notification system (push on mobile app, and 
pull on web), discuss storage/api, how to generate events, prefer to use 
periodical job to scan incoming events and generate messages accordingly
Round 5: Culture fit, strength, how to deal with disputes among colleagues, 
reverse linked list in pairs

Google:
1. Given a robot and a maze, the robot supports these apis:
Turn left, move forward, checkIsExit
Write a program to make it move to the exit

2. Design Youtube access control system, storage, scales

3. Suppose there are k threads, write a multi-thread program to make them 
come to deadlock, I use semaphore at first, then was asked to implement it 
with countDownLatch

4. RunLength encoding, discuss various ways to minimize the encoded string 
under different constraints

5. Design a system to generate Ids for distributed DBs, discuss various 
Zookeeper patterns (leader elections etc).
For a given number, how to return minimum number of squares that sums up to 
this number