꿈꾸는공학도

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..

이번 문제는 Linked list를 C 코드로 구현하는 것인데, 특이점은 각 Node가 Stack 구조라는 것이다.즉 아래와 같이 Linked list Node가 존재한다는 것!  다시 말하면, 밖에서 봤을 땐 하나의 커다란 Stack인데 이것들이 내부에선 Linked list로 구성이 되어 있다는 것이다.문제의 조건은 아래와 같다.   1. 각 Stack Node에는 Max-capacity가 존재하다. Max-capacity를 넘어서면 새로운 Stack Node를 만든다.   2. list_size() method를 구현하라. 현재 원소가 존재하는 List Node(stack)의 개수를 반환한다.   3. push() method를 구현하라.   4. pop() method를 구현하라. 원소가 Link..

https://leetcode.com/problems/minimum-number-of-operations-to-sort-a-binary-tree-by-level/description/?envType=daily-question&envId=2024-12-23You are given the root of a binary tree with unique values.In one operation, you can choose any two nodes at the same level and swap their values.Return the minimum number of operations needed to make the values at each level sorted in a strictly increasin..

class Solution: def leftmostBuildingQueries(self, heights: List[int], queries: List[List[int]]) -> List[int]: ans = [] # O(n^2 sol..) for i in range(len(queries)): # low & high are index high = max(queries[i]) low = min(queries[i]) if high == low or heights[high] > heights[low] : ans.append(high) co..