꿈꾸는공학도

https://leetcode.com/problems/lru-cache/description/DBMS Buffer에 Data를 Replace 하는 대표적인 Algorithm 중 하나인 LRU 방법에 대해 Implementation을 해보는 실습을 해본다. 문제 Description은 아래와 같다.Design 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 ..

https://leetcode.com/problems/unique-binary-search-trees/description/Given an integer n, return the number of structurally unique BST's (binary search trees) which has exactly n nodes of unique values from 1 to n. Example 1:Input: n = 3Output: 5Example 2:Input: n = 1Output: 1 Constraints:1 그래도 가볍게나마 BST문제도 풀어봐야지..! Linked List , Tree 이런 걸 자꾸만 건들자 근데 이건,, Tree 문제라기보단 수학 문제 같다.. 흐음..  1. Python 일단..

https://leetcode.com/problems/minimum-number-of-operations-to-move-all-balls-to-each-box/description/?envType=daily-question&envId=2025-01-06You have n boxes. You are given a binary string boxes of length n, where boxes[i] is '0' if the ith box is empty, and '1' if it contains one ball.In one operation, you can move one ball from a box to an adjacent box. Box i is adjacent to box j if abs(i - j)..

https://leetcode.com/problems/count-vowel-strings-in-ranges/description/?envType=daily-question&envId=2025-01-02You are given a 0-indexed array of strings words and a 2D array of integers queries.Each query queries[i] = [li, ri] asks us to find the number of strings present in the range li to ri (both inclusive) of words that start and end with a vowel.Return an array ans of size queries.length,..

https://leetcode.com/problems/minimum-cost-for-tickets/description/?envType=daily-question&envId=2024-12-31You have planned some train traveling one year in advance. The days of the year in which you will travel are given as an integer array days. Each day is an integer from 1 to 365.Train tickets are sold in three different ways:a 1-day pass is sold for costs[0] dollars,a 7-day pass is sold for..

https://leetcode.com/problems/count-ways-to-build-good-strings/description/?envType=daily-question&envId=2024-12-30Given the integers zero, one, low, and high, we can construct a string by starting with an empty string, and then at each step perform either of the following:Append the character '0' zero times.Append the character '1' one times.This can be performed any number of times.A good stri..

https://leetcode.com/problems/maximum-frequency-stack/description/Design a stack-like data structure to push elements to the stack and pop the most frequent element from the stack.Implement the FreqStack class:FreqStack() constructs an empty frequency stack.void push(int val) pushes an integer val onto the top of the stack.int pop() removes and returns the most frequent element in the stack.If t..

https://leetcode.com/problems/best-sightseeing-pair/description/?envType=daily-question&envId=2024-12-27You are given an integer array values where values[i] represents the value of the ith sightseeing spot. Two sightseeing spots i and j have a distance j - i between them.The score of a pair (i  values[i] + values[j] + i - j: the sum of the values of the sightseeing spots, minus the distance bet..

Algorithm Part의 기본적인 Data Structure인 Heap에 대해서 Implementation 연습을 시작해본다. Heap의 경우 Priority Queue라고도 생각하면 되고, Max/Min Heap으로 구분된다. 특징으론 Max Heap을 예로 들었을 때, Heap Data 구조에 입력되는 Data는 크기가 큰 순서(Max)대로 우선순위를 갖은 체 저장된다. 이 말은, Heap에서 특정 Data를 꺼낼 때(Deque) 가장 크기가 큰 녀석이 추출되는 것이다. 일반적으로 우리가 아는 queue구조에서 우선 순위만 선입선출이 아닌, Data 크기에 따라 결정된다는 것을 알고 있으면 된다. 따라서, 내부에 저장된 Data를 임의로 Search 할 수는 없지만 우리가 정한 Logic( Max..

https://leetcode.com/problems/find-minimum-diameter-after-merging-two-trees/description/?envType=daily-question&envId=2024-12-24There exist two undirected trees with n and m nodes, numbered from 0 to n - 1 and from 0 to m - 1, respectively. You are given two 2D integer arrays edges1 and edges2 of lengths n - 1 and m - 1, respectively, where edges1[i] = [ai, bi] indicates that there is an edge be..