Blind75

Blind 75 Questions with Solutions

Blind 75 Questions with Solutions

Think you’re ready for your coding interview?

Blind 75 will make sure you are.

Blind 75 is the go-to list to smash if you aim to do well in a technical interview. This list contains top coding interview questions that all the big tech giants will target you with.
Blind 75 has it all covered from arrays, strings, linked lists to trees, graphs, and dynamic programming.
Blind75

Two Pointers & Co.

Learn the Two Pointers technique and related patterns to efficiently solve array, string, and linked list problems.

Question
Difficulty
Solution

Valid Palindrome

Write a function that accepts a string s as input and checks whether it is a palindrome.

Easy

3Sum

Medium

Container with Most Water

Medium

Product of Array Except Self

Medium

Remove Nth Node from End of List

Medium

Linked List Cycle

Easy

Find minimum in rotated sorted array

Medium

Search in rotated sorted array

Medium

Basic Data Structures

Build a strong foundation in fundamental data structures like arrays, stacks, queues, and hash maps.

Question
Difficulty
Solution

Reorder List

Given the head of a singly linked list, reorder it as if it were folded on itself.

Medium

Reverse Linked List

Easy

Valid Parentheses

Easy

Set Matrix Zeroes

Medium

Rotate Image

Medium

Spiral Matrix

Medium

Exploring the Solution Space

Learn and apply tree depth-first search, tree breadth-first search, and backtracking patterns to efficiently solve problems.

Question
Difficulty
Solution

Binary Tree Level Order Traversal

Given a binary tree, return an array representing its level-order traversal. Each level's node values should be stored in separate sub-arrays, ordered from left to right.

Medium

Serialize and Deserialize Binary Tree

Hard

Binary Tree Maximum Path Sum

Hard

Build Binary Tree from Preorder and Inorder Traversal

Easy

Invert Binary Tree

Easy

Kth Smallest Element in a BST

Medium

Lowest Common Ancestor of a Binary Tree

Medium

Maximum Depth of a Binary Tree

Easy

Same Tree

Easy

Subtree of Another Tree

Easy

Validate Binary Search Tree

Medium

Word Search

Medium

Heaps, Hashing, and Tracking

Use heaps, hashing, and efficient tracking techniques to optimize search, sorting, and frequency counting.

Question
Difficulty
Solution

Valid Anagram

Given two strings, str1 and str2, check whether str2 is an anagram of str1.

Easy

Contains Duplicate

Easy

Group Anagrams

Medium

Two Sum

Easy

Top K Frequent Elements

Medium

Find Median from Data Stream

Hard

Fusion

Combine problem-solving techniques like merge intervals and K-way merge patterns to tackle coding interview problems.

Question
Difficulty
Solution

Insert Interval

Given a sorted list of nonoverlapping intervals and a new interval, insert the new interval into the correct position while ensuring that the resulting list of intervals remains sorted and nonoverlapping.

Medium

Merge Intervals

Medium

Meeting Rooms

Easy

Meeting Rooms II

Medium

Non-overlapping Intervals

Medium

Merge Sorted Array

Easy

Merge K Sorted Lists

Hard

Optimization Techniques

Learn advanced optimization techniques like memoization, greedy algorithms, pruning, and bit manipulation to solve questions.

Question
Difficulty
Solution

Jump game

In a jump game, the player starts at index 0 of an array nums and moves up to s steps, where s is the current value. Write a function to check if reaching the last index is possible, returning TRUE if yes, else FALSE.

Medium

Coin change

Medium

Longest Increasing Subsequence

Medium

Climbing Stairs

Easy

Combination Sum

Medium

Counting Bits

Easy

House Robber

Medium

House Robber II

Medium

Longest Common Subsequence

Medium

Longest Palindromic Substring

Medium

Maximum Product Subarray

Medium

Palindromic Substrings

Medium

Unique Paths

Medium

Word Break

Medium

Decode Ways

Medium

Maximum Subarray

Medium

Advanced Data Structures & Sorting Techniques

Find out how to practice tries, graphs, cyclic sort and topological sort patterns to solve coding problems.

Question
Difficulty
Solution

Implement Trie (Prefix Tree)

Implement a trie data structure with three functions that perform Insert (word), Search (word), and Search prefix (prefix).

Medium

Design Add and Search Words Data Structure

Easy

Word Search II

Hard

Pacific Atlantic Water Flow

Medium

Clone Graph

Medium

Graph Valid Tree

Medium

Alien Dictionary

Hard

Course Schedule

Medium

Missing Number

Easy

Elegant by Design

Practice the bitwise manipulation, sliding window, and union find patterns to crack coding interview problems.

Question
Difficulty
Solution

Encode and Decode Strings

Create encode to convert a string array into a single string for transmission. Create decode to restore the original array from the encoded string.

Medium

Number of 1 Bits

Easy

Reverse Bits

Easy

Sum of Two Integers

Medium

Best Time to Buy and Sell Stock

Easy

Longest Substring without Repeating Characters

Medium

Longest Repeating Character Replacement

Medium

Minimum Window Substring

Hard

Number of Islands

Medium

Longest Consecutive Sequence

Medium

Number of Connected Components in an Undirected Graph

Medium