꿈꾸는공학도

def smallest_pos_int(arr:list[int]) -> int: s = set() # 1) 양의 정수만 s 에 저장 for num in arr: if num > 0: s.add(num) # 2) 1부터 n+1까지 차례대로 s에 존재하는지 확인 n = len(arr) # 정답은 잘 해봐야 n+1이다..................... for i in range(1, n+2): # n+1 까지 확인, range 범위를 위해 n+2 if i not in s: # 집합 membership check: 평균 O(1) return i # 위 for문에서 항상 return이 ..

https://leetcode.com/problems/convert-sorted-list-to-binary-search-tree/description/Given the head of a singly linked list where elements are sorted in ascending order, convert it to a height-balanced binary search tree. Example 1:Input: head = [-10,-3,0,5,9]Output: [0,-3,9,-10,null,5]Explanation: One possible answer is [0,-3,9,-10,null,5], which represents the shown height balanced BST.Example ..

간단한 Tree 구조를 만들어서 Python 과 C 프로그래밍으로 Tree를 Traversal 하는 code를 짜봤다.첨부 파일을 통해서 실습을 진행할 수 있으며, Main 함수로 결과를 직접 확인해볼 수 있다. 요런 형태의 Tree로 테스트해봤는데, 마음대로 Tree구조를 바꿔서 Test 해봐도 된다.

https://leetcode.com/problems/subtree-of-another-tree/description/Given the roots of two binary trees root and subRoot, return true if there is a subtree of root with the same structure and node values of subRoot and false otherwise.A subtree of a binary tree tree is a tree that consists of a node in tree and all of this node's descendants. The tree tree could also be considered as a subtree of ..

https://leetcode.com/problems/combination-sum/description/Given an array of distinct integers candidates and a target integer target, return a list of all unique combinations of candidates where the chosen numbers sum to target. You may return the combinations in any order.The same number may be chosen from candidates an unlimited number of times. Two combinations are unique if the frequency of ..

https://leetcode.com/problems/subsets/description/Given an integer array nums of unique elements, return all possible subsets (the power set).The solution set must not contain duplicate subsets. Return the solution in any order. Example 1:Input: nums = [1,2,3]Output: [[],[1],[2],[1,2],[3],[1,3],[2,3],[1,2,3]]Example 2:Input: nums = [0]Output: [[],[0]] Constraints:1 -10 All the numbers of nums ar..

DBMS는 기본적으로 Multi User가 사용하기에, 모든 user가 사용해도 사용자 Transaction간 충돌이 없어야 한다. 그래서 중요한 것이 Index Concurrency!Data처리의 병행성, 동시성을 보장하는 녀석이다.

Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order. Example 1:Input: nums = [1,2,3]Output: [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]Example 2:Input: nums = [0,1]Output: [[0,1],[1,0]]Example 3:Input: nums = [1]Output: [[1]] Constraints:1 -10 All the integers of nums are unique.뭔가 기본적인 컨셉의 문제인데, 이게 또 한 번쯤은 집고 넘어가줘야 찝찝한게 없다..

https://leetcode.com/problems/reverse-linked-list-ii/description/Given the head of a singly linked list and two integers left and right where left  left to position right, and return the reversed list. Example 1:Input: head = [1,2,3,4,5], left = 2, right = 4Output: [1,4,3,2,5]Example 2:Input: head = [5], left = 1, right = 1Output: [5] Constraints:The number of nodes in the list is n.1 -500 1  Fo..

https://leetcode.com/problems/swapping-nodes-in-a-linked-list/description/You are given the head of a linked list, and an integer k.Return the head of the linked list after swapping the values of the kth node from the beginning and the kth node from the end (the list is 1-indexed). Example 1:Input: head = [1,2,3,4,5], k = 2Output: [1,4,3,2,5]Example 2:Input: head = [7,9,6,6,7,8,3,0,9,5], k = 5Ou..