Top DSA Interview Questions & Answers

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130 pages · 320 questions

What Is Big O Notation?
3 questions 1 easy 1 med 1 hardFree
O(n) vs O(log n): Why It Matters
2 questions 1 easy 1 medFree
Time vs Space Complexity
3 questions 1 easy 1 med 1 hardFree
Big O of Common Array and Hash Operations
2 questions 1 easy 1 medFree
Best, Worst and Average Case Explained
3 questions 1 easy 1 med 1 hardFree
What Is Amortized Complexity?
2 questions 1 med 1 hardFree
How Do You Analyze Nested Loops?
3 questions 1 easy 1 med 1 hardFree
What Is the Complexity of Recursive Calls?
2 questions 1 easy 1 medFree
Which Complexities Do Sorting Algorithms Have?
3 questions 1 easy 1 med 1 hardFree
Complexity Questions Interviewers Love
2 questions 1 med 1 hardFree
How Do You Solve Two Sum?
3 questions 1 easy 1 med 1 hardFree
What Is the Two Pointers Technique?
2 questions 1 easy 1 medFree
Removing Duplicates In Place
3 questions 1 easy 1 med 1 hardFree
How Do You Move Zeroes to the End?
2 questions 1 easy 1 medFree
Solving Container With Most Water
3 questions 1 easy 1 med 1 hardFree
How Do You Solve 3Sum?
2 questions 1 med 1 hardFree
What Is Kadane's Algorithm?
3 questions 1 easy 1 med 1 hardFree
Best Time to Buy and Sell Stock
2 questions 1 easy 1 medFree
How Do You Rotate an Array?
3 questions 1 easy 1 med 1 hardFree
Merging Two Sorted Arrays
2 questions 1 med 1 hardFree
Longest Substring Without Repeating Characters
3 questions 1 easy 1 med 1 hardFree
What Is the Sliding Window Technique?
2 questions 1 easy 1 medFree
Solving Minimum Window Substring
3 questions 1 easy 1 med 1 hardFree
How Do You Check Anagrams?
2 questions 1 easy 1 medFree
Longest Palindromic Substring
3 questions 1 easy 1 med 1 hardFree
Reverse Words vs Reverse Characters
2 questions 1 med 1 hardFree
How Do You Group Anagrams?
2 questions 1 easy 1 medFree
Finding the Longest Common Prefix
2 questions 1 med 1 hardFree
Counting Palindromic Substrings
3 questions 1 easy 1 med 1 hardFree
What Do Hash Map Questions Test?
3 questions 1 easy 1 med 1 hardFree
Hash Lookup vs Array Lookup
2 questions 1 easy 1 medFree
Finding the First Unique Character
3 questions 1 easy 1 med 1 hardFree
Intersection of Two Arrays
2 questions 1 easy 1 medFree
Subarray Sum Equals K
3 questions 1 easy 1 med 1 hardFree
What Is the Prefix Sum Technique?
2 questions 1 med 1 hardFree
Longest Consecutive Sequence
3 questions 1 easy 1 med 1 hardFree
The Frequency Counting Pattern
2 questions 1 easy 1 medFree
Detecting Duplicates Efficiently
2 questions 1 med 1 hardFree
Which Sorting Algorithm When?
3 questions 1 easy 1 med 1 hardFree
Quicksort vs Mergesort
2 questions 1 easy 1 medFree
Implementing Binary Search Correctly
3 questions 1 easy 1 med 1 hardFree
What Is Binary Search on the Answer?
2 questions 1 easy 1 medFree
Searching a Rotated Sorted Array
3 questions 1 easy 1 med 1 hardFree
First and Last Position in a Sorted Array
2 questions 1 med 1 hardFree
Finding the Kth Largest Element
3 questions 1 easy 1 med 1 hardFree
Meeting Rooms: Interval Overlap
2 questions 1 easy 1 medFree
Merging Overlapping Intervals
2 questions 1 med 1 hardFree
What Do Recursion Questions Test?
3 questions 1 easy 1 med 1 hardFree
Generating All Subsets
2 questions 1 easy 1 medFree
Generating All Permutations
3 questions 1 easy 1 med 1 hardFree
Solving Combination Sum
2 questions 1 easy 1 medFree
Solving N-Queens
3 questions 1 easy 1 med 1 hardFree
Word Search on a Grid
2 questions 1 med 1 hardFree
The Backtracking Template
3 questions 1 easy 1 med 1 hardFree
Memoization vs Tabulation
2 questions 1 easy 1 medFree
Tower of Hanoi Explained
2 questions 1 med 1 hardFree
Reversing a Linked List
3 questions 1 easy 1 med 1 hardFree
Detecting a Cycle
2 questions 1 easy 1 medFree
Merging Two Sorted Lists
3 questions 1 easy 1 med 1 hardFree
Removing the Nth Node from the End
2 questions 1 easy 1 medFree
Finding the Middle Node
3 questions 1 easy 1 med 1 hardFree
The Fast and Slow Pointers Pattern
2 questions 1 med 1 hardFree
Designing an LRU Cache
3 questions 1 easy 1 med 1 hardFree
Adding Numbers Stored in Lists
2 questions 1 easy 1 medFree
Reordering a List In Place
2 questions 1 med 1 hardFree
Valid Parentheses Check
3 questions 1 easy 1 med 1 hardFree
Designing a Min Stack
2 questions 1 easy 1 medFree
Next Greater Element
3 questions 1 easy 1 med 1 hardFree
Daily Temperatures Problem
2 questions 1 easy 1 medFree
What Is a Monotonic Stack?
3 questions 1 easy 1 med 1 hardFree
Building a Queue from Stacks
2 questions 1 med 1 hardFree
Sliding Window Maximum
3 questions 1 easy 1 med 1 hardFree
Designing a Circular Queue
2 questions 1 easy 1 medFree
Largest Rectangle in a Histogram
2 questions 1 med 1 hardFree
Maximum Depth of a Binary Tree
3 questions 1 easy 1 med 1 hardFree
Inorder, Preorder and Postorder
2 questions 1 easy 1 medFree
Level Order Traversal
3 questions 1 easy 1 med 1 hardFree
Validating a Binary Search Tree
2 questions 1 easy 1 medFree
Lowest Common Ancestor
3 questions 1 easy 1 med 1 hardFree
Inverting a Binary Tree
2 questions 1 med 1 hardFree
Diameter of a Binary Tree
3 questions 1 easy 1 med 1 hardFree
Path Sum Problems
2 questions 1 easy 1 medFree
Serializing and Deserializing Trees
2 questions 1 med 1 hardFree
Heap vs Priority Queue
3 questions 1 easy 1 med 1 hardFree
Top K Frequent Elements
2 questions 1 easy 1 medFree
Kth Largest in a Stream
3 questions 1 easy 1 med 1 hardFree
Merging K Sorted Lists
2 questions 1 easy 1 medFree
The Two Heaps Pattern
3 questions 1 easy 1 med 1 hardFree
Finding the Median of a Stream
2 questions 1 med 1 hardFree
Task Scheduler Problem
2 questions 1 easy 1 medFree
Last Stone Weight
2 questions 1 med 1 hardFree
How Does Heapify Work?
3 questions 1 easy 1 med 1 hardFree
BFS vs DFS: When to Use Which?
3 questions 1 easy 1 med 1 hardFree
Number of Islands
2 questions 1 easy 1 medFree
Adjacency List vs Matrix
3 questions 1 easy 1 med 1 hardFree
Detecting Cycles (Course Schedule)
2 questions 1 easy 1 medFree
Cloning a Graph
3 questions 1 easy 1 med 1 hardFree
Rotting Oranges
2 questions 1 med 1 hardFree
Flood Fill
3 questions 1 easy 1 med 1 hardFree
Word Ladder
2 questions 1 easy 1 medFree
Counting Connected Components
2 questions 1 med 1 hardFree
How Does Dijkstra's Algorithm Work?
3 questions 1 easy 1 med 1 hardFree
Bellman-Ford and Negative Weights
2 questions 1 easy 1 medFree
Topological Sorting
3 questions 1 easy 1 med 1 hardFree
Union-Find (Disjoint Set)
2 questions 1 med 1 hardFree
Minimum Spanning Trees
3 questions 1 easy 1 med 1 hardFree
Cheapest Flights Within K Stops
2 questions 1 easy 1 medFree
Network Delay Time
2 questions 1 easy 1 hardFree
Checking If a Graph Is Bipartite
2 questions 1 med 1 hardFree
Shortest Path in Unweighted Graphs
3 questions 1 easy 1 med 1 hardFree
What Is Dynamic Programming?
3 questions 1 easy 1 med 1 hardFree
Fibonacci with DP
2 questions 1 easy 1 medFree
Climbing Stairs
3 questions 1 easy 1 med 1 hardFree
House Robber
2 questions 1 med 1 hardFree
Coin Change
3 questions 1 easy 1 med 1 hardFree
Longest Common Subsequence
2 questions 1 easy 1 medFree
0/1 Knapsack
3 questions 1 easy 1 med 1 hardFree
Longest Increasing Subsequence
2 questions 1 easy 1 hardFree
Edit Distance
3 questions 1 easy 1 med 1 hardFree
Unique Paths
2 questions 1 med 1 hardFree
Greedy vs Dynamic Programming
3 questions 1 easy 1 med 1 hardFree
Jump Game
2 questions 1 easy 1 medFree
Recognizing the Pattern Fast
3 questions 1 easy 1 med 1 hardFree
How Do You Run a Mock Interview?
2 questions 1 easy 1 medFree
Stating Complexity Under Pressure
3 questions 1 easy 1 med 1 hardFree
Which DSA Questions Get Asked Most?
2 questions 1 med 1 hardFree
A Practice Routine That Compounds
2 questions 1 easy 1 medFree
Coding on a Whiteboard or Shared Doc
3 questions 1 easy 1 med 1 hardFree
Behavioral Basics for SDE Roles
2 questions 1 med 1 hardFree
Capstone: a Mixed Problem Marathon
3 questions 1 easy 1 med 1 hardFree

What Is Big O Notation?

O(n) vs O(log n): Why It Matters

Time vs Space Complexity

Big O of Common Array and Hash Operations

Best, Worst and Average Case Explained

What Is Amortized Complexity?

How Do You Analyze Nested Loops?

What Is the Complexity of Recursive Calls?

Which Complexities Do Sorting Algorithms Have?

Complexity Questions Interviewers Love

How Do You Solve Two Sum?

What Is the Two Pointers Technique?

Removing Duplicates In Place

How Do You Move Zeroes to the End?

Solving Container With Most Water

How Do You Solve 3Sum?

What Is Kadane's Algorithm?

Best Time to Buy and Sell Stock

How Do You Rotate an Array?

Merging Two Sorted Arrays

Longest Substring Without Repeating Characters

What Is the Sliding Window Technique?

Solving Minimum Window Substring

How Do You Check Anagrams?

Longest Palindromic Substring

Reverse Words vs Reverse Characters

How Do You Group Anagrams?

Finding the Longest Common Prefix

Counting Palindromic Substrings

What Do Hash Map Questions Test?

Hash Lookup vs Array Lookup

Finding the First Unique Character

Intersection of Two Arrays

Subarray Sum Equals K

What Is the Prefix Sum Technique?

Longest Consecutive Sequence

The Frequency Counting Pattern

Detecting Duplicates Efficiently

Which Sorting Algorithm When?

Quicksort vs Mergesort

Implementing Binary Search Correctly

What Is Binary Search on the Answer?

Searching a Rotated Sorted Array

First and Last Position in a Sorted Array

Finding the Kth Largest Element

Meeting Rooms: Interval Overlap

Merging Overlapping Intervals

What Do Recursion Questions Test?

Generating All Subsets

Generating All Permutations

Solving Combination Sum

Solving N-Queens

Word Search on a Grid

The Backtracking Template

Memoization vs Tabulation

Tower of Hanoi Explained

Reversing a Linked List

Detecting a Cycle

Merging Two Sorted Lists

Removing the Nth Node from the End

Finding the Middle Node

The Fast and Slow Pointers Pattern

Designing an LRU Cache

Adding Numbers Stored in Lists

Reordering a List In Place

Valid Parentheses Check

Designing a Min Stack

Next Greater Element

Daily Temperatures Problem

What Is a Monotonic Stack?

Building a Queue from Stacks

Sliding Window Maximum

Designing a Circular Queue

Largest Rectangle in a Histogram

Maximum Depth of a Binary Tree

Inorder, Preorder and Postorder

Level Order Traversal

Validating a Binary Search Tree

Lowest Common Ancestor

Inverting a Binary Tree