Grind 75 - Elite DSA Documentation

Welcome to the Grind 75 track. This is a collection of 75 high-impact LeetCode problems designed for rigorous technical interview preparation, focusing on identifying patterns and developing mental models.

Each problem file contains:

• A clear problem statement
• A step-by-step approach and solution strategy
• The optimal JavaScript (ES2022+) solution
• Recognition patterns

Topics & Progress

Dive into the problems below, structured by the standard 8-week Grind 75 progression.

Problem index

All write-ups live under problems/ — use this list as the canonical entry point:

• 001. Two Sum
• 003. Longest Substring Without Repeating Characters
• 005. Longest Palindromic Substring
• 008. String to Integer (atoi)
• 011. Container With Most Water
• 015. 3Sum
• 017. Letter Combinations of a Phone Number
• 020. Valid Parentheses
• 021. Merge Two Sorted Lists
• 023. Merge k Sorted Lists
• 033. Search in Rotated Sorted Array
• 039. Combination Sum
• 042. Trapping Rain Water
• 046. Permutations
• 053. Maximum Subarray
• 054. Spiral Matrix
• 056. Merge Intervals
• 057. Insert Interval
• 062. Unique Paths
• 067. Add Binary
• 070. Climbing Stairs
• 075. Sort Colors
• 076. Minimum Window Substring
• 078. Subsets
• 079. Word Search
• 084. Largest Rectangle in Histogram
• 098. Validate Binary Search Tree
• 102. Binary Tree Level Order Traversal
• 104. Maximum Depth of Binary Tree
• 105. Construct Binary Tree from Preorder and Inorder Traversal
• 110. Balanced Binary Tree
• 121. Best Time to Buy and Sell Stock
• 121. Best Time to Buy and Sell Stock
• 125. Valid Palindrome
• 127. Word Ladder
• 133. Clone Graph
• 139. Word Break
• 141. Linked List Cycle
• 146. LRU Cache
• 150. Evaluate Reverse Polish Notation
• 155. Min Stack
• 169. Majority Element
• 199. Binary Tree Right Side View
• 200. Number of Islands
• 206. Reverse Linked List
• 207. Course Schedule
• 208. Implement Trie (Prefix Tree)
• 217. Contains Duplicate
• 224. Basic Calculator
• 226. Invert Binary Tree
• 230. Kth Smallest Element in a BST
• 232. Implement Queue using Stacks
• 235. Lowest Common Ancestor of a Binary Search Tree
• 235. Lowest Common Ancestor of a BST
• 236. Lowest Common Ancestor of a Binary Tree
• 238. Product of Array Except Self
• 242. Valid Anagram
• 278. First Bad Version
• 295. Find Median from Data Stream
• 297. Serialize and Deserialize Binary Tree
• 310. Minimum Height Trees
• 322. Coin Change
• 383. Ransom Note
• 409. Longest Palindrome
• 416. Partition Equal Subset Sum
• 438. Find All Anagrams in a String
• 542. 01 Matrix
• 543. Diameter of Binary Tree
• 621. Task Scheduler
• 704. Binary Search
• 721. Accounts Merge
• 733. Flood Fill
• 876. Middle of the Linked List
• 876. Middle of the Linked List
• 973. K Closest Points to Origin
• 981. Time Based Key-Value Store
• 994. Rotting Oranges
• 1235. Maximum Profit in Job Scheduling