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Learn Data Structures and Algorithms in Java

Problem: All O`one Data Structure

Understand how to build the All One data structure that maintains string keys with frequency counts. Explore implementing efficient operations for incrementing, decrementing, and retrieving keys with maximum or minimum counts, all in O(1) time using a doubly linked list and hash maps.

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Statement

Design a data structure that stores string keys along with their frequencies and supports efficient updates and queries.

Implement the AllOne class:

  • AllOne() → Initializes the data structure.

  • inc(key) → Increases the count of key by 1. If the key does not exist, insert it with count 1.

  • dec(key) → Decreases the count of key by 1. If the count becomes 0, remove the key. It is guaranteed the key exists when dec is called.

  • getMaxKey() → Returns any key with the highest count. If empty, return "" ...