Algorithms
My LeetCode topic strength, scored from every logged study session — recency-decayed, difficulty-weighted, floor-protected once a topic has been mastered. The polygon shrinks when I slack. That's the point.
Problems Tap a problem to test yourself on its specific tricks. Nothing is tracked or stored.
Arrays & hashing 1 · Two sum 3 cards 49 · Group anagrams 3 cards 217 · Contains duplicate 2 cards 242 · Valid anagram 3 cards Sliding window 3 · Longest substring without repeating characters 3 cards 209 · Minimum size subarray sum 4 cards Binary search 35 · Search insert position 2 cards 704 · Binary search 3 cards Stacks & queues 20 · Valid parentheses 3 cards Linked lists 19 · Remove nth node from end of list 3 cards 21 · Merge two sorted lists 4 cards 141 · Linked list cycle 4 cards 142 · Linked list cycle II 3 cards 206 · Reverse linked list 3 cards Trees 100 · Same tree 3 cards 102 · Binary tree level order traversal 3 cards 104 · Maximum depth of binary tree 2 cards 226 · Invert binary tree 3 cards 572 · Subtree of another tree 2 cards Heaps 215 · Kth largest element in an array 2 cards 973 · K closest points to origin 3 cards Graphs 200 · Number of islands 3 cards Dynamic programming 70 · Climbing stairs 3 cards Greedy & intervals 56 · Merge intervals 4 cards Recent work 283 · Move zeroes learning session · 2026-07-25 125 · Valid palindrome practice session · 2026-07-25 100 · Same tree cold solve · 2026-07-25 19 · Remove nth node from end of list cold solve · 2026-07-25 21 · Merge two sorted lists practice session · 2026-07-25 226 · Invert binary tree cold solve · 2026-06-01 19 · Remove nth node from end of list learning session · 2026-06-01 142 · Linked list cycle II learning session · 2026-06-01 141 · Linked list cycle learning session · 2026-06-01 21 · Merge two sorted lists learning session · 2026-06-01 35 · Search insert position cold solve · 2026-05-25 167 · Two sum II — input array is sorted cold solve · 2026-05-25 49 · Group anagrams practice session · 2026-05-25 572 · Subtree of another tree learning session · 2026-05-25 102 · Binary tree level order traversal learning session · 2026-05-25 100 · Same tree learning session · 2026-05-25 226 · Invert binary tree learning session · 2026-05-25 242 · Valid anagram practice session · 2026-05-23 167 · Two sum II — input array is sorted learning session · 2026-05-23 35 · Search insert position learning session · 2026-05-23 209 · Minimum size subarray sum learning session · 2026-05-23 973 · K closest points to origin learning session · 2026-05-23 206 · Reverse linked list practice session · 2026-05-23 56 · Merge intervals practice session · 2026-05-23 78 · Subsets practice session · 2026-05-23 70 · Climbing stairs practice session · 2026-05-23 200 · Number of islands practice session · 2026-05-23 56 · Merge intervals learning session · 2026-05-22 78 · Subsets learning session · 2026-05-22 70 · Climbing stairs learning session · 2026-05-22 200 · Number of islands learning session · 2026-05-22 215 · Kth largest element in an array practice session · 2026-05-22 104 · Maximum depth of binary tree practice session · 2026-05-22 206 · Reverse linked list practice session · 2026-05-22 20 · Valid parentheses practice session · 2026-05-22 704 · Binary search practice session · 2026-05-22 3 · Longest substring without repeating characters practice session · 2026-05-22 125 · Valid palindrome practice session · 2026-05-22 1 · Two sum practice session · 2026-05-22 215 · Kth largest element in an array learning session · 2026-05-21 104 · Maximum depth of binary tree learning session · 2026-05-21 206 · Reverse linked list learning session · 2026-05-21 20 · Valid parentheses learning session · 2026-05-21 704 · Binary search learning session · 2026-05-21 3 · Longest substring without repeating characters learning session · 2026-05-21 125 · Valid palindrome learning session · 2026-05-21 217 · Contains duplicate practice session · 2026-05-21 217 · Contains duplicate practice session · 2026-05-20
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