☕ Amazon Fails

Hey,

Hope you’re having a fantastic day!

Interview Problem

What is Leader Election in the context of System Design and Distributed Computing?

We’ll send a detailed solution tomorrow, so make sure you move our emails to primary, so you don’t miss them!

Gmail users—move us to your primary inbox

• On your phone? Hit the 3 dots at top right corner, click "Move to" then "Primary"

• On desktop? Back out of this email then drag and drop this email into the "Primary" tab near the top left of your screen

Apple mail users—tap on our email address at the top of this email (next to "From:" on mobile) and click “Add to VIPs”

Industry News

Amazon cancels Crucible, it’s free to play multiplayer shooter

If you’re like most people, you were probably unaware that Amazon had a free-to-play multiplayer shooter called Crucible. It was Amazon’s response to Fortnite, the massive free-to-play, team-based shooter by Epic Games. The company planned to integrate it further with Twitch, a video game streaming service that Amazon acquired in 2014. Crucible was launched in May after years of development (it was first announced in 2016), but Amazon put it back into closed beta in July (due to abysmal traction).

Now, the company has cancelled Crucible, just five months after release. They’ll be giving users a full refund for any purchases made (through microtransactions) and servers will stay up until November 9th for custom games. The financial loss for this kind of termination would be in the tens of millions of dollars.

If you’re familiar with Amazon’s culture, however, this kind of failure is no big surprise. Amazon thrives on bold mistakes so that the company can continue to innovate fearlessly. After Amazon’s massive failure with the Fire Phone in 2015 (resulting in the loss of hundreds of millions of dollars), Bezos sent the following message to the leader of the Fire Phone project.

“You can’t, for one minute, feel bad about the Fire Phone. Promise me you won’t lose a minute of sleep”

This kind of culture is how you build a trillion dollar company.

This is also not the end for Amazon’s gaming interests, it’s just the beginning. Amazon is investing heavily in a cloud gaming service called Luna that was launched last month. Luna offers all-you-can-play access to different selections of games as part of separate “channels”, similar to a cable service. An example is the Ubisoft channel, which gives users a bundle of Ubisoft games. You purchase access to the channel and get all the games contained.

Digital mental health subscription service Cerebral raises $35 million dollars

The mental health market is incredibly hot in digital health. In the first half of 2020, digital behavioral health companies raised $588 million dollars in funding, with several companies receiving over $100 million dollars. Headspace is one of those companies with a Series C round that was over $100 million dollars.

Cerebral is another company in the space and has raised $35 million dollars in their Series A. The company offers a membership service where clients can get telehealth visits with a mental health provider and monthly chats with a care counselor. The provider can come up with a treatment plan, which may include medication. They can then use Cerebral to ship the medication to clients through mail and see the patient’s symptoms and side-effects through the app.

Cerebral will be using the $35 million dollars to expand into all 50 states and also expand partnerships with insurers. The money was raised in a round led by Oak HealthCare with participation from Liquid 2 Ventures, Gaingels and Air Angels.

Previous Solution

As a refresher, here’s the previous question

Given two integers n and k, return all possible combinations of k numbers out of 1 to n inclusive.

You can return the answer in any order!

Input - n = 4, k = 3

Output - [[1,2,3],[1,2,4],[1,3,4],[2,3,4]]

Solution

This question is quite similar to the permutations question we sent out a couple of days ago.

The way you solve it is through backtracking or DFS.

In backtracking, you

1. Make a Choice

2. Explore that Choice until you’ve reached an end

3. Undo the Choice

So, in terms of building finding all the combinations of n characters that are of length k, we first start with the empty string, then we backtrack

1. Make a choice - pick one of the n characters to add to our string

2. Explore the choice - recursively call our function on the remaining n - 1 characters and k - 1 spots, until we run out spots (k will always be less than n). When we run out of spots (k), then we add our string to a set where we keep track of all combinations.

3. Undo the choice - delete that one of n characters that we picked.

Here’s the Python 3 code (with test cases!) for how we can do this.