꿈꾸는공학도

https://leetcode.com/problems/swap-nodes-in-pairs/description/Given a linked list, swap every two adjacent nodes and return its head. You must solve the problem without modifying the values in the list's nodes (i.e., only nodes themselves may be changed.) Example 1:Input: head = [1,2,3,4]Output: [2,1,4,3]Explanation:Example 2:Input: head = []Output: []Example 3:Input: head = [1]Output: [1]Exampl..

C - 2개 / C++ - 2개 이렇게 총 4개의 코딩문제를 3시간에 거쳐서 풀어보았다. 문제는 Time / Space Complexcity를 크게 고려하지 않고, 정답만 도출되면 인정되는 부분이라 어거지로 코드를 짜서 답을 도출해내는 데에는 성공을 했으나.. 앞으로 좀 더 효율적인 코딩을 하기 위해선 Coding Review정도는 하고 넘어가는 것이 좋을 거 같아 글을 적어본다. 문제의 출처도 제공되진 않지만, 시험이 끝나고 내가 스스로 복기 + 구글링/GPT를 이용해서 문제 출처를 추려내어 보았다.  1번 문제https://school.programmers.co.kr/learn/courses/30/lessons/42627 프로그래머스SW개발자를 위한 평가, 교육, 채용까지 Total Solution을..

https://leetcode.com/problems/maximum-difference-between-node-and-ancestor/description/Given the root of a binary tree, find the maximum value v for which there exist different nodes a and b where v = |a.val - b.val| and a is an ancestor of b.A node a is an ancestor of b if either: any child of a is equal to b or any child of a is an ancestor of b. Example 1:Input: root = [8,3,10,1,6,null,14,nul..

https://leetcode.com/problems/the-k-weakest-rows-in-a-matrix/description/You are given an m x n binary matrix mat of 1's (representing soldiers) and 0's (representing civilians). The soldiers are positioned in front of the civilians. That is, all the 1's will appear to the left of all the 0's in each row.A row i is weaker than a row j if one of the following is true:The number of soldiers in row..

Python / C / C++에서 Array / Linked List 기반으로 heap 구조를 만들어보겠다. Skeleton Code는 GPT를 참고했으며, Min/Max heap은 사실 한 끝 차이라 이 둘을 그냥 번갈아가면서 구현해보기로 한다. 1. Python - Array - Min heapclass PriorityQueueArray: def __init__(self, is_min=True): self.heap = [] self.is_min = is_min # True for min-heap, False for max-heap def parent(self, i): return (i - 1) // 2 def left_child(self, i):..

https://leetcode.com/problems/implement-queue-using-stacks/description/Implement a first in first out (FIFO) queue using only two stacks. The implemented queue should support all the functions of a normal queue (push, peek, pop, and empty).Implement the MyQueue class:void push(int x) Pushes element x to the back of the queue.int pop() Removes the element from the front of the queue and returns i..

https://leetcode.com/problems/battleships-in-a-board/description/Given an m x n matrix board where each cell is a battleship 'X' or empty '.', return the number of the battleships on board.Battleships can only be placed horizontally or vertically on board. In other words, they can only be made of the shape 1 x k (1 row, k columns) or k x 1 (k rows, 1 column), where k can be of any size. At least..

https://leetcode.com/problems/maximal-square/description/Given an m x n binary matrix filled with 0's and 1's, find the largest square containing only 1's and return its area. Example 1:Input: matrix = [["1","0","1","0","0"],["1","0","1","1","1"],["1","1","1","1","1"],["1","0","0","1","0"]]Output: 4Example 2:Input: matrix = [["0","1"],["1","0"]]Output: 1Example 3:Input: matrix = [["0"]]Output: 0..

https://leetcode.com/problems/min-cost-to-connect-all-points/description/You are given an array points representing integer coordinates of some points on a 2D-plane, where points[i] = [xi, yi].The cost of connecting two points [xi, yi] and [xj, yj] is the manhattan distance between them: |xi - xj| + |yi - yj|, where |val| denotes the absolute value of val.Return the minimum cost to make all poin..

https://leetcode.com/problems/valid-palindrome/description/A phrase is a palindrome if, after converting all uppercase letters into lowercase letters and removing all non-alphanumeric characters, it reads the same forward and backward. Alphanumeric characters include letters and numbers.Given a string s, return true if it is a palindrome, or false otherwise. Example 1:Input: s = "A man, a plan, ..