Leetcode#380. Insert Delete GetRandom O(1)
ProblemImplement the RandomizedSet class:
RandomizedSet() Initializes the RandomizedSet object.
bool insert(int val) Inserts an item val into the set if not present. Returns true if the item was not present, false otherwise.
bool remove(int val) Removes an item val from the set if present. Returns true if the item was present, false otherwise.
int getRandom() Returns a random element from the current set of elements (it’s guaranteed that at least one element exists when this method is called). ...
Leetcode#855. Exam Room
ProblemThere is an exam room with n seats in a single row labeled from 0 to n - 1.
When a student enters the room, they must sit in the seat that maximizes the distance to the closest person. If there are multiple such seats, they sit in the seat with the lowest number. If no one is in the room, then the student sits at seat number 0.
Design a class that simulates the mentioned exam room.
Implement the ExamRoom class:
ExamRoom(int n) Initializes the object of the exam room with the number of th ...
Leetcode#933. Number of Recent Calls
ProblemYou have a RecentCounter class which counts the number of recent requests within a certain time frame.
Implement the RecentCounter class:
RecentCounter() Initializes the counter with zero recent requests.
int ping(int t) Adds a new request at time t, where t represents some time in milliseconds, and returns the number of requests that has happened in the past 3000 milliseconds (including the new request). Specifically, return the number of requests that have happened in the inclusive ran ...
Leetcode#146. LRU Cache
ProblemDesign a data structure that follows the constraints of a Least Recently Used (LRU) cache.
Implement the LRUCache class:
LRUCache(int capacity) Initialize the LRU cache with positive size capacity.
int get(int key) Return the value of the key if the key exists, otherwise return 1.
void put(int key, int value) Update the value of the key if the key exists. Otherwise, add the key-value pair to the cache. If the number of keys exceeds the capacity from this operation, evict the least recent ...