Cracking a FAANG Interview with Recursion

Cracking a FAANG Interview with Recursion
Cracking a FAANG Interview with Recursion


FAANG interviews are becoming more challenging, and preparing for them is not a simple process. There is no end to the kinds of questions that may be asked in the interview, and many of them are difficult. The “toughest” questions are different for each individual.

What is simple for you may be difficult for someone else, and vice versa. Therefore, it is critical to prepare for your FAANG interview, regardless of what the “hardest” questions are. 

What is FAANG?

For practically all engineering students and graduates, working at Facebook, Amazon, Apple, Netflix, or Google (FAANG) is a dream come true. The FAANG companies continue to be the most sought-after employers for engineers, with over 50k interview applications each week.

Tips for Approaching FAANG Recursion Problems

1. Always think about the base case

If a recursion question arises during a technical interview, it is usually advisable to start with the end in mind or the base case. A recursive function comprises two components.

The first is a basic case in which the call to the function terminates. That is, no further recursive calls are made. The recursive case is the second half of a recursive function, in which the function calls itself until it reaches the base case.

It’s necessary to keep in mind that your base case guarantees that the programme will quit. Otherwise, your programme will continue to execute indefinitely.

2. Spot a recursion question

Remember when the probability and word problems were all the rage? They told you that anytime you heard the word “and,” you multiplied the possibilities, and when you heard “or,” you added them. This notion is comparable to programming, specifically recursion.

When you hear terms such as “tree,” “graph,” “linked list,” or “nested,” this is a good indicator that you should utilise recursion. These are almost certainly dead giveaways that you’ll need to conduct a recursive function of some kind.

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3. Consider the following questions while you work

If you are asked a technical question concerning recursion in a FAANG interview, it is vital to consider the following.

  • What is most likely the base case?
  • What is the most basic recursive case I can solve? Then, elaborate on it.
  • How does your approach to problem-solving affect the stack? Further, consider how you may improve on it.

The Six Fundamental Recursive Patterns

One of the key reasons why individuals struggle with recursion is they lack a mental model for interpreting recursion as a whole. It might be tough to figure out what is going on when you look at each recursive problem and realise how diverse they are.

Not only that, how can you be convinced that you will be able to solve a problem in your interview if every issue seems to be entirely different?

1. Iteration

Any recursive problem may also be solved iteratively, and vice versa. This is a basic idea in functional languages, where everything is done via recursion; there are no loops.

For iteration, we simply execute our recursive function on the remaining inputs, either by passing in the next node or by incrementing some index. While it isn’t observed very frequently, this is one of the most basic implementations of recursion.

2. Selection

Selection is one of the most popular patterns in recursion and dynamic programming. In this pattern, we are simply looking for all of the combinations of our input that meet a certain set of criteria.

3. Ordering

Ordering is a permutation of selection’s combination. Essentially, we’re interested in any case wherein we wish to explore multiple orderings of our values.

4. Divide and Conquer

If you’re familiar with some of the most prevalent uses of recursion, you’ve probably seen this one coming. Divide and conquer is at the heart of how we employ algorithms such as mergesort, binary search, depth-first search, and others. In this technique, we try to divide the problem space in half, solve each half individually, and then rejoin.

5. Depth-first Search

The last pattern that the recursive functions may fall under is depth-first search (DFS). It’s also one you’ll most likely find yourself utilising because DFS and breadth-first search (BFS) are often employed whenever we deal with trees or graphs.

The most crucial aspect of DFS is to comprehend not only how to search for a node in a tree or graph but also how to discover the path itself. If you can’t do that, you’re considerably restricting your options. You can employ DFS as part of a larger problem rather than modifying it significantly in most circumstances. As a result, it is critical to know the fundamentals of how DFS works.

Important Algorithms Asked in FAANG Interviews

The following algorithms are asked in FAANG interviews.

Frequently Asked Questions

Is recursion important for coding interviews?

Recursion is the foundation of logic, local variables, the call-stack, and much more. It utilises a logic-driven intuitive cognitive approach. One of the most prevalent reasons individuals want to comprehend recursion is because it’s frequently asked during interviews.

How do you master recursion?

The most straightforward technique to master recursion is to choose a language in which you wish to study recursion. Then, construct a simple programme to compute a factorial with Fibonacci series and various intricate programmes that can be solved using recursion.

Should I use recursion in interviews?

You should use recursion in interviews because it often provides for a stunningly easy algorithmic solution to problems that would otherwise be almost impossible to solve using an iterative algorithm. Recursive problems are natural problems, and the best way to think about them is via recursion.

Is backtracking important for an interview?

Backtracking is crucial for an interview because employers use it to eliminate a huge number of candidates with a single test. It is often significantly quicker than brute force enumeration of all candidates.

How do I know if I have backtracking problems?

You can begin by checking the first box; if it does not contain the coin, you should shut it and go to the second box, and so on, until you discover the coin. Backtracking is the process of addressing all sub-problems one by one to arrive at the best potential answer in the algorithm’s search tree.

How do I practice backtracking?

Solve recursion and backtracking practice questions to put your programming abilities to the test. To further deepen your understanding, go through detailed tutorials.

Which FAANG company is the best to work for?

Netflix and Facebook are the two best FAANG companies to work for.

Key Takeaways

Now that you understand why FAANG is such a big deal for all engineers, it is evident how difficult it would be to get into these top-tier businesses.

FAANG requires hard work, passion, commitment, and a strong will to succeed. Cracking the interviews of the FAANG organisations is not an easy task. One must be prepared to outperform the competition. Structured learning and effort are essential.