Google Interview Experience L3/L4
February 6, 2022
Edit [for 3.5 years experienced - L3/L4 level]
Few tips and suggestions sharing in the end.
Phone Interview:
There is a grasshopper that starts from the root node, if the hopper hops to a node with no children the hopper is stuck and can't move further. If the grasshopper has the option to move then it has to make the hop. Basically the goal is to find the probability of the grasshopper landing at each node.
image
For given graph, return probability map for each of node at time = INFINITY;
Q2: Same question in a directed acyclic graph?
image
Google Onsite Rounds:
Round 1
Q1: Given a list of tasks (a task have id, arrivalTime and executionTime)
At any point of time from a pool of pending tasks task with minimum execution time will be picked up first by the core.
and a single core processor to execute those tasks. You need to find the order of execution of jobs.
(
https://leetcode.com/problems/single-threaded-cpu/)
Followup : Modify the code to get the order of processing using 2 cores processor.
Round 2
Q1 Given an array of building heights.
You are starting at first building. You have b (no of bricks) and r(no. of ropes). You can only move by 1 building at a time. To move to the next building,
If next building height is less or equal you can move without using any resource(bricks/ropes).
If next building height is greater you can either use bricks (1 brick for 1 unit of height) or a rope(you can climb any height using rope).
(
https://leetcode.com/discuss/interview-question/528584/Google-or-Onsite-or-How-Far-Can-We-Reach-using-Rope-and-Bricks/465758)
(
https://leetcode.com/problems/furthest-building-you-can-reach/)
find the maximum distance you can cover using given array, b and r.
Round 3
Q1: Given an array of N distinct unsorted integers. Return a list of numbers which can be found in the array using binary search.
Ex: If the array is [4, 3, 5, 8, 9, 6, 7] answer: 3, 5, 8, 10
(
https://leetcode.com/discuss/interview-question/352743/Google-or-Onsite-or-Guaranteed-Binary-Search-Numbers)
Followup
how to prevent dynamic growing of arrayList which is storing result?
Round 4
There is a country that has multiple cities, and for simplicity each city has a 3-letter name. Some pairs of cities are connected with roads. Example:
Your friend recently took a trip around some of that country's cities. You ask them what their itinerary was, and they say: "I went to AAA, BBB, CCC, DDD in that order."
You quickly realize your friend must have misremembered, as this itinerary is impossible. BBB is not connected to CCC, and DDD doesn't exist. But, with a two-letter change, you can make a valid itinerary: AAA, XBB, CCC, DDY so you guess that was your friend's actual itinerary. You could also consider AAA, BBB, GOO, DDY, but that requires 4 letters to change so it's not as good of a guess.
Minimise the cost to validate the itenerary.
(
https://leetcode.jp/problemdetail.php?id=1548#:~:text=You need to return the,[i %2B 1] ).)
Round 5 (Googlyness)
Tell something about a project that you are satisfied with/and proud of.
Tell about an instance where you faced interpersonal problems with people around you.
Tell about an experience when you have worked with a non performer in your team and how you helped them.
Tell about the problem where you faced challenges in working with them as peer.
Result:
My rounds went well as per me despite during prep I only did around 90-100 Leetcode questions (60+-med, 20-30-easy, rest hard) so was feeling underprep.
I was able to propose solutions in each of round. And able to optimise the solutions and code them as well.
Though during feedback communication via HR, in R4 and R3 there were gaps, and these were the rounds I was thinking were gone relatively better were the ones where interviewer pin pointed my mistakes harder and the ones which I was thinking that I screwed up like R2, feedbacks were actually good.
Common feedback was around good DS and algo and communication skills, but slow coding and took some hints in resolving few of the edge cases.
HR sent my profile for L3 to HC also parallely started team matching for expediting the process. I got a team match- HM was very cool and confident to meet. I started building hopes. But unfortunately HC result doesn't turned out to be positive.
Tips/lesson learned:
Believe me, almost everytime you will feel that you are underprepared, no matter how much practice you do. I watched youtube 15-20 mins before interview to distract my self and be less nervous for interview. That helped me to not overthink and not let nervousness impact my thinking ability.
Interviewers were very very nice, In R2 I came across such an amazing person who was not letting me down. I optimised my solutions as much as I can and every time she was asking for more optimised.. whenever she felt I was blank she proposed a hint. Inbetween I did quit on myself, but she didn't and she constantly trying to understand my point of view. And despite of all this hassle her feedback was best out of all. She was one of the best interviewers I came across in my carrer, not because of her good feedback but because of her primary focus point to evaluate was based on what and how I am thinking.
They were expecting to write code in 5 mins once algortithm is identified. So practice accordingly.
If you are taking hints/help that is considered as -ve, in my experience.
They only ask you to write code for best possible solution, till that time they keep on grilling you to optimise the approach. In R2 I proposed 4 algorithms and then jumped to coding.
Also I was doing constant commuication with interviewers that was the positive part.
For those who are in the process or about to be a part of it, I would suggest to do quality practice as I only did few leetcode questions but the quality is something I focused on, practice till you are able to recognize the pattern of question and relate it to few agorithms that you are aware of. Every question is just a tweak in some standard problems. Make sure to cover maximum categories of patterns.
Also its okay to search stupid stuff related to process on Quora/Over internet, to be nerovous, to be curious, to roam around the room everyday and refreshing your gmail for an update from HR. Everybody who goes through process feels same. So you are not alone.. only suggestion is dont overthink and talk to freinds who calm you down!
Resources:
I practiced around 20-30 days if I am not wrong parallel to office, and believe me finding practice time was relatively easier during these virtual times. I have done basic level of DS and Algo in previous switches/college placements so I didn't started from scratch.
Overall though outcome was not in my favour, but indeed one of the best interview experiences I ever had. Good quality questions, with sensible interviewers, amazing coordinating HR's and transparent process(Except HC ofcourse).