Blind 75 LeetCode Questions

LeetCode is a popular platform for practicing coding problems, especially when preparing for technical interviews. The "Blind 75" is a collection of 75 carefully selected questions from LeetCode that are particularly useful for interview preparation. These questions cover a range of topics and difficulty levels, and they are chosen based on their frequency and importance in real interviews.

This collection is divided into several categories, such as arrays, strings, linked lists, trees, dynamic programming, and more. Each category contains a mix of easy, medium, and hard problems, allowing you to gradually build your skills.

Array

• Two Sum (Easy) HashMap Solution
• Best Time to Buy and Sell Stock (Easy) Two Pointer Solution
• Contains Duplicate (Easy) HashSet Solution
• Product of Array Except Self (Medium) Prefix and Suffix product array Solution
• Maximum Subarray (Medium) Kadane's algorithm (Dynamic Programming) Solution
• Maximum Product Subarray (Medium) Kadane's algorithm (Dynamic Programming) Solution
• Find Minimum in Rotated Sorted Array (Medium) Binary Search Solution
• Search in Rotated Sorted Array (Medium) Binary Search Solution
• 3Sum (Medium) Two Pointer Solution
• Container With Most Water (Medium) Two Pointer Solution

Binary

• Sum of Two Integers (Medium) Bit Manipulation Solution
• Number of 1 Bits (Easy) Bit Manipulation Solution
• Counting Bits (Easy) Bit Manipulation (Dynamic Programming) Solution
• Missing Number (Easy) Bit Manipulation Solution
• Reverse Bits (Easy) Bit Manipulation Solution

Dynamic Programming

• Climbing Stairs (Easy) Dynamic Programming Solution
• Coin Change (Medium) Dynamic Programming Solution
• Longest Increasing Subsequence (Medium) Dynamic Programming Solution
• Longest Common Subsequence (Medium) Dynamic Programming Solution
• Word Break Problem (Medium) Dynamic Programming Solution
• Combination Sum (Medium) Dynamic Programming Solution
• House Robber (Medium) Dynamic Programming Solution
• House Robber II (Medium) Dynamic Programming Solution
• Decode Ways (Medium) Dynamic Programming Solution
• Unique Paths (Medium) Dynamic Programming Solution
• Jump Game (Medium) Dynamic Programming Solution

Graph

• Clone Graph (Medium) Graph Traversal Solution
• Course Schedule (Medium) Topological Sort Solution
• Pacific Atlantic Water Flow (Medium) Graph Traversal Solution
• Number of Islands (Medium) Graph Traversal Solution
• Longest Consecutive Sequence (Medium) Graph Traversal Solution
• Alien Dictionary (Leetcode Premium) (Medium) Topological Sort
• Graph Valid Tree (Leetcode Premium) (Medium) Graph Traversal
• Number of Connected Components in an Undirected Graph (Leetcode Premium) (Medium) Graph Traversal

Interval

• Insert Interval (Medium) Interval Solution
• Merge Intervals (Medium) Interval Solution
• Non-overlapping Intervals (Medium) Interval Solution
• Meeting Rooms (Leetcode Premium) (Medium) Interval
• Meeting Rooms II (Leetcode Premium) (Medium) Interval

Linked List

• Reverse a Linked List (Easy) Linked List Solution
• Detect Cycle in a Linked List (Easy) Linked List Two Pointers Solution
• Merge Two Sorted Lists (Easy) Linked List Solution
• Merge K Sorted Lists (Hard) Linked List Divide and Conquer Solution
• Remove Nth Node From End Of List (Medium) Linked List Solution
• Reorder List (Medium) Linked List Solution

Matrix

• Set Matrix Zeroes (Easy) Matrix Solution
• Spiral Matrix (Medium) Matrix right,left,top,bottom Solution
• Rotate Image (Medium) Matrix change rows with columns then rotate each row Solution
• Word Search (Medium) Matrix DFS Solution

String

• Longest Substring Without Repeating Characters (Medium) Sliding Window Solution
• Longest Repeating Character Replacement (Medium) Sliding Window Solution
• Minimum Window Substring (Hard) Sliding Window Solution
• Valid Anagram (Easy) HashMap Solution
• Group Anagrams (Medium) HashMap Solution
• Valid Parentheses (Easy) Stack Solution
• Valid Palindrome (Easy) Two Pointer Solution
• Longest Palindromic Substring (Medium) Two Pointer expand around center Solution
• Palindromic Substrings (Medium) Two Pointer Solution
• Encode and Decode Strings (Leetcode Premium) (Medium) String

Tree

• Maximum Depth of Binary Tree (Easy) Tree Traversal Solution
• Same Tree (Easy) Tree Traversal Solution
• Invert/Flip Binary Tree (Easy) Tree Traversal Solution
• Binary Tree Maximum Path Sum (Hard) Tree Traversal Solution
• Binary Tree Level Order Traversal (Medium) Tree Traversal Solution
• Serialize and Deserialize Binary Tree (Hard) Tree Traversal Solution
• Subtree of Another Tree (Easy) Tree Traversal Solution
• Construct Binary Tree from Preorder and Inorder Traversal (Medium) Tree Traversal Solution
• Validate Binary Search Tree (Medium) Tree Traversal Solution
• Kth Smallest Element in a BST (Medium) Tree Traversal Solution
• Lowest Common Ancestor of BST (Medium) Tree Traversal Solution
• Implement Trie (Prefix Tree) (Medium) Tree Traversal Solution
• Add and Search Word (Medium) Tree Traversal Solution
• Word Search II (Hard) Tree Traversal Solution

Heap

• Merge K Sorted Lists (Hard) Heap Solution
• Top K Frequent Elements (Medium) Heap Solution
• Find Median from Data Stream (Hard) Heap Solution

Important Link:

14 Patterns to Ace Any Coding Interview Question

How to Use This List

• Start with Basics: Begin with easier problems to build your confidence.
• Focus on Patterns: Identify common patterns and algorithms.
• Practice Regularly: Consistency is key in problem-solving.
• Review Solutions: Understand not just the how, but also the why behind each solution.
• Mock Interviews: Use these problems to simulate real interview scenarios.

Resources

• LeetCode
• Blind 75 Discussion Forum
• Coding Interview Resources
• LeetCode Patterns
• LeetCode Explore
• Blind 75 spreadsheet
• Coding Patterns

Remember, the goal is not just to solve all 75 problems, but to understand the underlying principles and patterns that will enable you to tackle any new problem with confidence.