Grind 75 — LeetCode Study Plan

The Grind 75 is the modern successor to the Blind 75, by the same author — a balanced 75-problem list covering the patterns interviews test most. Here is the full list, grouped by topic. Problems with a link have a full write-up — key idea, solution, and a step-by-step visualization — and every one is built to review with spaced repetition so the pattern sticks.

We have 75 of these with full solutions.

Arrays & Hashing

• Two SumEASY
• Valid AnagramEASY
• Ransom NoteEASY
• Majority ElementEASY
• Contains DuplicateEASY
• Product of Array Except SelfMEDIUM

Two Pointers

• Valid PalindromeEASY
• 3SumMEDIUM
• Sort ColorsMEDIUM
• Container With Most WaterMEDIUM
• Trapping Rain WaterHARD

Sliding Window

• Best Time to Buy and Sell StockEASY
• Longest Substring Without Repeating CharactersMEDIUM
• Find All Anagrams in a StringMEDIUM
• Minimum Window SubstringHARD

Stack

• Valid ParenthesesEASY
• Implement Queue using StacksEASY
• Evaluate Reverse Polish NotationMEDIUM
• Min StackMEDIUM
• Basic CalculatorHARD
• Largest Rectangle in HistogramHARD

Binary Search

• Binary SearchEASY
• First Bad VersionEASY
• Search in Rotated Sorted ArrayMEDIUM
• Time Based Key-Value StoreMEDIUM

Linked List

• Merge Two Sorted ListsEASY
• Linked List CycleEASY
• Reverse Linked ListEASY
• Middle of the Linked ListEASY
• LRU CacheMEDIUM

Trees

• Invert Binary TreeEASY
• Lowest Common Ancestor of a Binary Search TreeMEDIUM
• Balanced Binary TreeEASY
• Diameter of Binary TreeEASY
• Maximum Depth of Binary TreeEASY
• Binary Tree Level Order TraversalMEDIUM
• Validate Binary Search TreeMEDIUM
• Lowest Common Ancestor of a Binary TreeMEDIUM
• Binary Tree Right Side ViewMEDIUM
• Construct Binary Tree from Preorder and Inorder TraversalMEDIUM
• Kth Smallest Element in a BSTMEDIUM
• Serialize and Deserialize Binary TreeHARD

Tries

• Implement Trie (Prefix Tree)MEDIUM

Heap / Priority Queue

• K Closest Points to OriginMEDIUM
• Task SchedulerMEDIUM
• Find Median from Data StreamHARD
• Merge k Sorted ListsHARD

Backtracking

• Combination SumMEDIUM
• PermutationsMEDIUM
• SubsetsMEDIUM
• Letter Combinations of a Phone NumberMEDIUM
• Word SearchMEDIUM

Graphs

• Flood FillEASY
• 01 MatrixMEDIUM
• Clone GraphMEDIUM
• Course ScheduleMEDIUM
• Number of IslandsMEDIUM
• Rotting OrangesMEDIUM
• Accounts MergeMEDIUM
• Minimum Height TreesMEDIUM
• Word LadderHARD

Dynamic Programming

• Climbing StairsEASY
• Maximum SubarrayMEDIUM
• Coin ChangeMEDIUM
• Word BreakMEDIUM
• Partition Equal Subset SumMEDIUM
• Unique PathsMEDIUM
• Longest Palindromic SubstringMEDIUM
• Maximum Profit in Job SchedulingHARD

Intervals

• Insert IntervalMEDIUM
• Merge IntervalsMEDIUM

String

• Longest PalindromeEASY
• String to Integer (atoi)MEDIUM

Math & Geometry

• Add BinaryEASY
• Spiral MatrixMEDIUM