I was interviewed at all the big companies, and Google gave the worst experience by far.

One screening interview – don't believe them when they say it's easy, because for me it was the hardest interview of all, so come prepared.

There were three LeetCode-style questions, one architecture design question, and one personal (Googliness) question.

Prepare for really unfriendly interviewers. It felt like they were forced to interview.

I was present with a card game.

There are x red cards and x black cards lying on the back.

Each turn, you can flip one card.

• If it’s a black card, you gain +1 point.
• If it’s a red card, you lose -1 point.

You can choose when to stop the game (you don’t have to flip all of them).

Write a function that, given the number x, returns the mean score of the game.

Example: 1 black card and 1 red card, the mean will be 0.5.

Explanation: There are only two options with the same probability:

• You pick the red card first, then continue and take the black. Score = 0.
• You pick the black card first and quit. Score = 1.

Mean = (1 * 0.5) + (0 * 0.5) = 0.5.

Note: Getting a red card and stopping the game without flipping the black card is a valid move, but it doesn’t make sense, so we don’t consider that move (same for picking black and then flipping red).