Design (41 completed) Back to top # Title Level Cats Solution Languages Date Complete 146 LRU Cache Medium N150 solution py Nov 10, 2025 155 Min Stack Medium N150 solution py Jun 16, 2024 170 Two Sum III - Data structure design Easy solution py Jul 31, 2024 173 Binary Search Tree Iterator Medium solution py Jun 26, 2024 208 Implement Trie (Prefix Tree) Medium B75, N150 solution py Jun 27, 2024 211 Design Add and Search Words Data Structure Medium B75, N150 solution py Jun 27, 2024 251 Flatten 2D Vector Medium solution py May 22, 2024 271 Encode and Decode Strings Medium B75, N150 solution py Jun 13, 2024 341 Flatten Nested List Iterator Medium solution java Jul 02, 2024 348 Design Tic-Tac-Toe Medium solution py Jul 05, 2024 353 Design Snake Game Medium solution py Jun 28, 2024 359 Logger Rate Limiter Easy solution py Mar 16, 2026 362 Design Hit Counter Medium solution py Oct 24, 2024 380 Insert Delete GetRandom O(1) Medium solution java Jul 06, 2024 381 Insert Delete GetRandom O(1) - Duplicates allowed Hard solution java Jul 06, 2024 384 Shuffle an Array Medium solution py Jun 29, 2024 431 Encode N-ary Tree to Binary Tree Hard solution java, py Jun 28, 2024 460 LFU Cache Hard solution py Nov 09, 2025 535 Encode and Decode TinyURL Medium solution py Jun 07, 2024 622 Design Circular Queue Medium solution py Jul 06, 2024 641 Design Circular Deque Medium solution py Sep 30, 2024 676 Implement Magic Dictionary Medium solution py Jun 27, 2024 703 Kth Largest Element in a Stream Easy Daily, N150 solution py Jul 05, 2024 707 Design Linked List Medium solution java Jun 22, 2024 729 My Calendar I Medium solution py Sep 26, 2024 895 Maximum Frequency Stack Hard solution java, py Jul 11, 2024 919 Complete Binary Tree Inserter Medium solution py Jul 05, 2024 981 Time Based Key-Value Store Medium N150 solution py Oct 24, 2024 1166 Design File System Medium solution py Jun 28, 2024 1261 Find Elements in a Contaminated Binary Tree Medium solution py Feb 21, 2025 1381 Design a Stack With Increment Operation Medium solution py Jul 06, 2024 1429 First Unique Number Medium solution py Oct 26, 2024 1472 Design Browser History Medium solution py Jul 06, 2024 1570 Dot Product of Two Sparse Vectors Medium solution c, java, py Jun 06, 2024 1756 Design Most Recently Used Queue Medium solution py Feb 15, 2025 1804 Implement Trie II (Prefix Tree) Medium solution py Jun 27, 2024 2013 Detect Squares Medium N150 solution py Jun 28, 2024 2043 Simple Bank System Medium solution py Oct 26, 2025 2349 Design a Number Container System Medium solution py Oct 28, 2024 2671 Frequency Tracker Medium solution py Jun 28, 2024 3242 Design Neighbor Sum Service Easy solution py Aug 04, 2024