오구리의 DevLog

▶100 - Same Tree ▶문제 Given the roots of two binary trees p and q, write a function to check if they are the same or not. Two binary trees are considered the same if they are structurally identical, and the nodes have the same value. ▶예제 Input: p = [1,2,3], q = [1,2,3] Output: true Input: p = [1,2], q = [1,null,2] Output: false Input: p = [1,2,1], q = [1,1,2] Output: false ▶풀이 나는 각 트리의 값들을 직접 저장해..

▶144 - Binary Tree Preorder Traversal ▶문제 Given the root of a binary tree, return the preorder traversal of its nodes' values. ▶예제 Input: root = [1,null,2,3] Output: [1,2,3] Input: root = [] Output: [] Input: root = [1] Output: [1] ▶풀이 자료구조 때 배운 방식으로 preorder를 구성해서 풀었다.preorder는 left, right를 가기 전에 현재 node의 value값을 저장하거나 출력하는 방식이다. # Definition for a binary tree node. # class TreeNode: # def __in..

▶149 - Max Points on a Line ▶문제 Given an array of points where points[i] = [xi, yi] represents a point on the X-Y plane, return the maximum number of points that lie on the same straight line. ▶예제 Input: points = [[1,1],[2,2],[3,3]] Output: 3 Input: points = [[1,1],[3,2],[5,3],[4,1],[2,3],[1,4]] Output: 4 ▶풀이 단순히 모든 점들을 확인해보는 방식을 사용했다. 시간 복잡도가 O(n^2)가 나오는 방식이라서 시간초과가 날까 봐 걱정했지만 통과가 되었다. 점들의 기울기 ..

▶134 - Gas Station ▶문제 There are n gas stations along a circular route, where the amount of gas at the ith station is gas[i]. You have a car with an unlimited gas tank and it costs cost[i] of gas to travel from the ith station to its next (i + 1)th station. You begin the journey with an empty tank at one of the gas stations. Given two integer arrays gas and cost, return the starting gas station'..

▶452 - Minimum Number of Arrows to Burst Balloons ▶문제 There are some spherical balloons taped onto a flat wall that represents the XY-plane. The balloons are represented as a 2D integer array points where points[i] = [xstart, xend] denotes a balloon whose horizontal diameter stretches between xstart and xend. You do not know the exact y-coordinates of the balloons. Arrows can be shot up directly..

▶1834 - Single-Threaded CPU ▶문제 You are given n​​​​​​ tasks labeled from 0 to n - 1 represented by a 2D integer array tasks, where tasks[i] = [enqueueTimei, processingTimei] means that the i​​​​​​th​​​​ task will be available to process at enqueueTimei and will take processingTimei to finish processing. You have a single-threaded CPU that can process at most one task at a time and will act in th..

▶55 - Jump Game ▶문제 You are given an integer array nums. You are initially positioned at the array's first index, and each element in the array represents your maximum jump length at that position. Return true if you can reach the last index, or false otherwise. ▶예제 Input: nums = [2,3,1,1,4] Output: true Explanation: Jump 1 step from index 0 to 1, then 3 steps to the last index. Input: nums = [3..

▶520 - Detect Capital ▶문제 We define the usage of capitals in a word to be right when one of the following cases holds: All letters in this word are capitals, like "USA". All letters in this word are not capitals, like "leetcode". Only the first letter in this word is capital, like "Google". Given a string word, return true if the usage of capitals in it is right. ▶예제 Input: word = "USA" Output: ..

▶290 - Word Pattern ▶문제 Given a pattern and a string s, find if s follows the same pattern. Here follow means a full match, such that there is a bijection between a letter in pattern and a non-empty word in s. ▶예제 Input: pattern = "abba", s = "dog cat cat dog" Output: true Input: pattern = "abba", s = "dog cat cat fish" Output: false Input: pattern = "aaaa", s = "dog cat cat dog" Output: false ▶..

▶980 - Unique Paths III ▶문제 You are given an m x n integer array grid where grid[i][j] could be: 1 representing the starting square. There is exactly one starting square. 2 representing the ending square. There is exactly one ending square. 0 representing empty squares we can walk over. -1 representing obstacles that we cannot walk over. Return the number of 4-directional walks from the starting..

▶309 - Best Time to Buy and Sell Stock with Cooldown ▶문제 You are given an array prices where prices[i] is the price of a given stock on the ith day. Find the maximum profit you can achieve. You may complete as many transactions as you like (i.e., buy one and sell one share of the stock multiple times) with the following restrictions: After you sell your stock, you cannot buy stock on the next da..

▶886 - Possible Bipartition ▶문제 We want to split a group of n people (labeled from 1 to n) into two groups of any size. Each person may dislike some other people, and they should not go into the same group. Given the integer n and the array dislikes where dislikes[i] = [ai, bi] indicates that the person labeled ai does not like the person labeled bi, return true if it is possible to split everyo..

▶841 - Keys and Rooms ▶문제 There are n rooms labeled from 0 to n - 1 and all the rooms are locked except for room 0. Your goal is to visit all the rooms. However, you cannot enter a locked room without having its key. When you visit a room, you may find a set of distinct keys in it. Each key has a number on it, denoting which room it unlocks, and you can take all of them with you to unlock the ot..

▶50 - Pow(x, n) ▶문제 Implement pow(x, n), which calculates x raised to the power n (i.e., xn). https://cplusplus.com/reference/valarray/pow/ function template std::pow template valarray pow (const valarray & x, const valarray & y);template valarray pow (const valarray & x, const T& y);template valarray pow (const T& x, const valarray & y); Compute power of valarray elements Returns a cplusplus.co..

▶1971 - Find if Path Exists in Graph ▶문제 There is a bi-directional graph with n vertices, where each vertex is labeled from 0 to n - 1 (inclusive). The edges in the graph are represented as a 2D integer array edges, where each edges[i] = [ui, vi] denotes a bi-directional edge between vertex ui and vertex vi. Every vertex pair is connected by at most one edge, and no vertex has an edge to itself...

▶380 - Insert Delete GetRandom O(1) ▶문제 Implement the RandomizedSet class: RandomizedSet() Initializes the RandomizedSet object. bool insert(int val) Inserts an item val into the set if not present. Returns true if the item was not present, false otherwise. bool remove(int val) Removes an item val from the set if present. Returns true if the item was present, false otherwise. int getRandom() Ret..

▶739 - Evaluate Reverse Polish Notation ▶문제 Given an array of integers temperatures represents the daily temperatures, return an array answer such that answer[i] is the number of days you have to wait after the ith day to get a warmer temperature. If there is no future day for which this is possible, keep answer[i] == 0 instead. ▶예제 Input: temperatures = [73,74,75,71,69,72,76,73] Output: [1,1,4,..

▶150 - Evaluate Reverse Polish Notation ▶문제 Evaluate the value of an arithmetic expression in Reverse Polish Notation. Reverse Polish notation - Wikipedia From Wikipedia, the free encyclopedia Jump to navigation Jump to search Mathematics notation where operators follow operands "Operational stack" redirects here. For the English Channel lorry parking procedure, see Operation Stack. Reverse Poli..

▶232 - Implement Queue using Stacks ▶문제 mplement 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 it. int peek() Returns the ele..

▶1143 - Longest Common Subsequence ▶문제 Given two strings text1 and text2, return the length of their longest common subsequence. If there is no common subsequence, return 0. A subsequence of a string is a new string generated from the original string with some characters (can be none) deleted without changing the relative order of the remaining characters. For example, "ace" is a subsequence of ..