You only need 25 questions to learn all the coding interview patterns Quiz

Master the most essential coding interview patterns with these key algorithmic questions selected to boost your data structures and algorithms skills.

1. Two-Pointer Pattern

   Which coding interview problem commonly uses the two-pointer technique where both pointers move towards each other from opposite ends of an array?

   1. Combination Sum
   2. Insert Interval
   3. Evaluate Reverse Polish Notation
   4. 3Sum

   Explanation: The two-pointer pattern is often used in the 3Sum problem, where pointers are moved inward from both ends to find triplets adding up to a target. Combination Sum relies on backtracking, Insert Interval involves merging rather than pointer movement, and Evaluate Reverse Polish Notation is stack-based.

2. Sliding Window Technique

   Which problem is a classic example of using a sliding window and a hash map together to find substrings quickly?

   1. Longest Substring Without Repeating Characters
   2. Product of Array Except Self
   3. Merge Intervals
   4. Min Stack

   Explanation: Longest Substring Without Repeating Characters efficiently uses a sliding window and a hash map to track previously seen characters. Min Stack deals with constant-time min retrieval, Product of Array Except Self uses prefix/suffix arrays, and Merge Intervals sorts and combines intervals but does not use a sliding window.

3. Prefix Product Array

   Which technique is fundamental in solving 'Product of Array Except Self' without using division?

   1. Sliding Window
   2. Prefix and Suffix Arrays
   3. Stack Simulation
   4. Heap Queue

   Explanation: Prefix and suffix arrays allow computation of array products for each element without including itself, avoiding division. Stack simulation and sliding window solve different problem types, while heap queue manages dynamic ordering operations, not product calculations.

4. Stack for Expression Evaluation

   Which problem demonstrates evaluating mathematical expressions with a stack, such as parsing postfix notation?

   1. Minimum Window Substring
   2. Evaluate Reverse Polish Notation
   3. Insert Interval
   4. Trapping Rain Water

   Explanation: Evaluate Reverse Polish Notation uses a stack to process operands and operators correctly in postfix format. Minimum Window Substring uses a sliding window, Insert Interval deals with merging, and Trapping Rain Water applies two-pointers or stacks for boundary calculations.

5. Interval Merging

   Which problem requires sorting intervals and merging overlapping ones to produce a list of non-overlapping intervals?

   1. Min Stack
   2. Trapping Rain Water
   3. Merge Intervals
   4. Combination Sum

   Explanation: Merge Intervals asks for overlapping intervals to be combined after sorting, resulting in a set of non-overlapping segments. Min Stack enables min retrieval, Combination Sum is about finding combinations, and Trapping Rain Water calculates water trapped between heights.