Data Structures Interview Questions
Common Data Structures Interview Questions
This module serves as a review, highlighting some of the most frequently asked questions in technical interviews. Mastering these patterns is key to success. Click on a problem name to view it on LeetCode.
Arrays & Strings
- Two Sum: A classic for a reason. Tests your knowledge of hash maps.
- Best Time to Buy and Sell Stock: A simple but effective way to test greedy thinking.
- Container with Most Water: A great test of the two-pointer technique.
- Longest Substring Without Repeating Characters: The canonical sliding window problem.
- Valid Parentheses: The perfect use case for a stack.
Linked Lists
- Reverse a Linked List: Iterative and recursive solutions are both important.
- Detect Cycle in a Linked List: Tests the fast & slow pointer (Floyd's Tortoise and Hare) algorithm.
- Merge Two Sorted Lists: A fundamental merging logic that's a building block for Merge Sort.
- Remove Nth Node From End of List: A clever use of two pointers with an offset.
Trees
- Maximum Depth of Binary Tree: A straightforward recursive problem.
- Invert Binary Tree: A classic problem that tests recursion and tree traversal.
- Validate Binary Search Tree: Requires careful traversal, passing down constraints (min/max values).
- Level Order Traversal: The canonical problem for Breadth-First Search (BFS) using a queue.
- Lowest Common Ancestor of a BST/BT: Tests understanding of BST properties and recursive traversal.
Graphs
- Number of Islands: A great problem for practicing DFS or BFS for traversal on a grid.
- Clone Graph: Tests understanding of graph traversal (DFS/BFS) and using a hash map to handle visited nodes and avoid cycles.
- Course Schedule: A classic topological sort problem, testing cycle detection in a directed graph.
- Pacific Atlantic Water Flow: A great problem for practicing traversal from multiple sources.
Dynamic Programming
- Climbing Stairs: A simple introduction to DP, solvable with the Fibonacci pattern.
- Coin Change: A classic unbounded knapsack-style problem.
- Longest Increasing Subsequence: A more advanced DP problem with a clever O(n log n) solution.