dsa4 min read
LRU Cache — Design with O(1) Get and Put
Implement an LRU (Least Recently Used) cache with O(1) get and put using a doubly linked list and hashmap. Full 5-language solutions.
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dsa4 min read
LFU Cache — O(1) Least Frequently Used Eviction
Implement an LFU cache with O(1) get and put. Uses two hashmaps and per-frequency doubly linked lists to track access frequency and recency simultaneously.
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dsa4 min read
Design Twitter — Social Media Feed with Top K Posts
Design a simplified Twitter where users post tweets and follow each other, with getNewsFeed returning the 10 most recent tweets from followed users using a min-heap merge.
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dsa2 min read
Design a File System — Trie-Based Path Storage
Implement a file system that creates paths and associates values with them. Uses a Trie or HashMap to map full paths to values with O(L) operations.
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dsa3 min read
Design Hit Counter — Count Requests in Last 300 Seconds
Design a hit counter that counts hits in the last 5 minutes using a deque-based sliding window or circular buffer with O(1) amortised operations.
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