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Table of contents
1.
Introduction
2.
Puzzle Description
3.
Solution
4.
Frequently Asked Questions
4.1.
What is a puzzle interview?
4.2.
How do you answer a puzzle in an interview?
4.3.
Why do we do puzzles in interviews?
5.
Conclusion
Last Updated: Mar 27, 2024

Quarters on a Table

Author Tashmit
0 upvote
Master Python: Predicting weather forecasts
Speaker
Ashwin Goyal
Product Manager @
Interview Puzzles

Introduction

A puzzle is a magnificent measure of one's analytical skills and lateral thinking. Many product-based companies ask the riddles to help them filter candidates based on their real-world problem-solving skills to approach a problem they have not seen before.

A puzzle may have multiple solutions. The interviewer is generally interested in the candidate's approach to solving the mystery and the approach to building and thinking creatively about the answer to the puzzle.

On the same note, we will discuss an exciting puzzle commonly asked in interviews; Quarters on a table

Puzzle Description

Assume the game is played among two players on a circular table of unknown diameter. Each player is provided with an infinite number of Quarters. They can take turns placing the coin on the table such that there are Quarters all over the table. If any player on their turn can not make a legal move, the other player wins. A legal move is when the coin can be placed on the table perfectly in a sufficient place with no overlapping among the other coins. Which player is guaranteed to win?

Assume that the table's diameter is greater than the coin's diameter.

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Solution

Player 1 will have a guaranteed win. 

Player 1's strategy will be to put the first coin at the center of the table. Then, Player 2 puts the coin anywhere on the table. Next, Player 1 will put his coin diametrically opposite to the coin placed by Player 2. The game will continue until the table is filled. Every position has a diametrically opposite direction on the table except for the center. Since Player 1 always has a spot diametrically opposite to Player 2's coin, Player 1 will win.

Illustration Image

Check out this problem - 8 Queens Problem

Frequently Asked Questions

What is a puzzle interview?

Puzzle interviewers ask applicants to solve puzzles to check their analytical thinking skills.

How do you answer a puzzle in an interview?

First of all, think about the problem and carefully understand the question interviewer is trying to ask. Ask for any clarifications, if there are any. Lastly, don't just tell the answer, but clearly explain the solution.

Why do we do puzzles in interviews?

Puzzles are generally asked to see how you go about solving tricky problems. 

Conclusion

This article extensively discussed Quarters on a table puzzle and provided its solution. We hope that this blog has helped you enhance your knowledge regarding Quarters on a table puzzle.

Recommended Readings:


Do check out The Interview guide for Product Based Companies as well as some of the Popular Interview Problems from Top companies like Amazon, Adobe, Google, etc. on Coding Ninjas Studio.

Also check out some of the Guided Paths on topics such as Interview Puzzles, Data Structure and Algorithms, Competitive Programming, Operating Systems, Computer Networks, DBMS, System Design, etc. as well as some Contests, Test Series, Interview Bundles, and some Interview Experiences curated by top Industry Experts only on Coding Ninjas Studio.

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