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 ..

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..

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..

https://leetcode.com/problems/maximum-employees-to-be-invited-to-a-meeting/description/?envType=daily-question&envId=2025-01-26A company is organizing a meeting and has a list of n employees, waiting to be invited. They have arranged for a large circular table, capable of seating any number of employees.The employees are numbered from 0 to n - 1. Each employee has a favorite person and they will..

https://leetcode.com/problems/make-lexicographically-smallest-array-by-swapping-elements/description/?envType=daily-question&envId=2025-01-25You are given a 0-indexed array of positive integers nums and a positive integer limit.In one operation, you can choose any two indices i and j and swap nums[i] and nums[j] if |nums[i] - nums[j]| Return the lexicographically smallest array that can be obtai..