Why Do Interviewers Ask Puzzles for Software Jobs: A Closer Look

When it comes to software engineering interviews, the inclusion of puzzles and brain teasers has been a subject of considerable controversy and debate. The traditional practice can be traced back to the early years of the modern tech industry, where large companies like Google were known to employ these methods. However, in recent years, the revelation that these techniques may not hold up to rigorous scrutiny has sparked new discussions and reflections.

Does the Use of Puzzles in Software Interviews Have a Hidden Reason?

The original question, posed in the early days of the internet, remains valid today: why do interviewers still rely on puzzling questions despite the admitted lack of correlation with future performance? In June 2013, Google acknowledged that their famous brain teasers were indeed ineffective. Yet, despite this, the practice persists in many tech companies. This article aims to explore the reasons behind this persistence, and whether there might be any hidden benefits beyond the initial assumptions.

The Authority Bias in Hiring

When we observe a major employer like Google applying a particular hiring technique, we tend to assume that they must have a good reason for doing so. This is known as the authority bias, and it can be quite powerful in shaping our perceptions. However, the truth is more complex. While tech interviews are indeed heavily scrutinized, the correlation between techniques and future engineering performance is not as straightforward as it might seem.

Case Study: The Pirate Captain Puzzle

To illustrate the complexity of these interview questions, let's delve into a classic example: the pirate captain's gold distribution puzzle. The puzzle presents a scenario where the captain of a ship needs to divide 204 gold coins among 100 pirates to avoid being voted off the ship. The rules are simple: the captain proposes a distribution, and more than half must agree for it to pass. If fewer than half agree, the captain is voted off, and the second-in-command becomes the new captain, proposing their own solution.

The Misleading Solution

Many articles suggest an optimal solution where the captain divides the gold evenly among the top 51 pirates while giving nothing to the remaining 49. However, this is far from the most effective strategy. Let's explore the more optimal solution:

Optimizing the Distribution

The optimal solution is to take 153 gold coins for oneself. Then, give 1 coin to each of the next 51 pirates. The remaining 48 pirates will receive nothing. Here's how the voting will go:

48 pirates will vote against the captain because they would get nothing. The second-in-command pirate (who would get 1 coin if the captain dies) will vote against the captain because they will still have a chance to propose their own distribution. The remaining 50 pirates will vote in favor of the captain because they stand to gain only 1 coin, which they cannot get after the captain dies.

Thus, the captain survives with 153 coins, while 51 pirates get 1 coin each, and 48 pirates get nothing, maximizing the captain's share of the gold.

Why Such Techniques Persist

While the effectiveness of brain teasers may be questioned, their persistence in software interviews can be attributed to several factors:

Cultural Continuity: The tradition of using these questions has become ingrained in the tech industry, making it difficult for new methods to replace them without significant upheaval. Mindset Testing: The puzzles are designed to test a candidate's ability to think outside the box and solve complex problems under pressure. This can be a valuable skill in software development. Perceived Fairness: While initial evidence suggests that these techniques may not predict future performance, many companies believe they are looking for a certain mindset or problem-solving ability that these questions can capture.

Moreover, these puzzles can serve as a psychological filter, quickly eliminating candidates who are annoyed by or ill-suited to such challenges, potentially allowing the company to focus on more promising applicants who can handle the pressure well.

Conclusion

Despite their questionable utility, brain teasers and other puzzle-based interview techniques continue to be a part of the software engineering interviewing process. While the reasons for their persistence may not be as straightforward as we once believed, the tradition likely remains due to cultural continuity, the testing of problem-solving skills, and the perceived fairness of such methods.

As the tech industry evolves, it will be interesting to see if more objective and equitable methods of assessing candidates' abilities and potential emerge. Until then, puzzle-based interviews are likely to remain a part of the hiring landscape.