[DSA] Coding Interview Preparation Quiz

Sharpen your skills for coding interviews with these key DSA patterns and problem-solving fundamentals. This quiz targets critical algorithmic approaches and clean coding principles.

1. Efficient Code Qualities

   Which quality is MOST important for code to be maintainable during interviews?

   1. Readable
   2. Obfuscated
   3. Hardcoded
   4. Short

   Explanation: Readable code is vital for maintainability, enabling easy understanding and future changes. Obfuscated code is difficult to interpret, short code can sometimes compromise clarity, and hardcoded values often reduce flexibility and break easily with requirements shifts.

2. Prefix and Suffix Sums

   What is the primary use case for prefix sum arrays in algorithm problems?

   1. Reversing strings
   2. Tracking element frequency
   3. Finding duplicate elements
   4. Calculating range sums efficiently

   Explanation: Prefix sum arrays quickly compute the sum of elements between indices, improving the efficiency of range queries. Tracking frequency requires maps or arrays for counting, finding duplicates relies on sets or hashing, and reversing strings does not use prefix sums.

3. Two Pointer Technique

   Which type of problem is BEST suited for the two pointer technique?

   1. Sorting an array in-place
   2. Calculating string permutations
   3. Finding pairs with a target sum in a sorted array
   4. Constructing a hash table

   Explanation: The two pointer technique excels at finding pairs or triplets meeting specific sums in sorted arrays by moving pointers inward. Sorting in-place doesn't require two pointers as the main approach, string permutations use recursion/backtracking, and hash tables are built differently.

4. Monotonic Stack Pattern

   What is the MAIN benefit of using a monotonic stack in algorithm challenges?

   1. Encoding strings
   2. Calculating prefix sums
   3. Finding next greater or smaller elements efficiently
   4. Counting substring frequencies

   Explanation: Monotonic stacks maintain increasing or decreasing order to efficiently solve problems involving next greater or smaller elements. Counting frequencies, encoding strings, and prefix sums do not utilize monotonic stacks.

5. Dynamic Programming Approaches

   How does the bottom-up approach (tabulation) in dynamic programming typically work?

   1. It reverses computed answers
   2. It stores all input permutations
   3. It memorizes results during recursive calls
   4. It iteratively builds a table from base cases to the final solution

   Explanation: The bottom-up (tabulation) approach constructs solutions starting from the simplest cases, filling a table as it progresses. Memoization is top-down with recursion, storing all permutations is too resource-intensive, and reversing answers is not inherent to DP.