소프트웨어에 대한 모든 것

문제) 150. Evaluate Reverse Polish Notation Evaluate the value of an arithmetic expression in Reverse Polish Notation. Valid operators are +, -, *, and /. Each operand may be an integer or another expression. Note that division between two integers should truncate toward zero. It is guaranteed that the given RPN expression is always valid. That means the expression would always evaluate to a resul..

문제) 1209. Remove All Adjacent Duplicates in String II You are given a string s and an integer k, a k duplicate removal consists of choosing k adjacent and equal letters from s and removing them, causing the left and the right side of the deleted substring to concatenate together. We repeatedly make k duplicate removals on s until we no longer can. Return the final string after all such duplicate..

문제) 2225. Find Players With Zero or One Losses You are given an integer array matches where matches[i] = [winneri, loseri] indicates that the player winneri defeated player loseri in a match. Return a list answer of size 2 where: answer[0] is a list of all players that have not lost any matches. answer[1] is a list of all players that have lost exactly one match. The values in the two lists shou..

문제) 451. Sort Characters By Frequency Given a string s, sort it in decreasing order based on the frequency of the characters. The frequency of a character is the number of times it appears in the string. Return the sorted string. If there are multiple answers, return any of them. Example 1: Input: s = "tree" Output: "eert" Explanation: 'e' appears twice while 'r' and 't' both appear once. So 'e'..

문제) 1704. Determine if String Halves Are Alike You are given a string s of even length. Split this string into two halves of equal lengths, and let a be the first half and b be the second half. Two strings are alike if they have the same number of vowels ('a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U'). Notice that s contains uppercase and lowercase letters. Return true if a and b are alike. O..

문제) 931. Minimum Falling Path Sum Given an n x n array of integers matrix, return the minimum sum of any falling path through matrix. A falling path starts at any element in the first row and chooses the element in the next row that is either directly below or diagonally left/right. Specifically, the next element from position (row, col) will be (row + 1, col - 1), (row + 1, col), or (row + 1, c..

문제) 2432. The Employee That Worked on the Longest Task There are n employees, each with a unique id from 0 to n - 1. You are given a 2D integer array logs where logs[i] = [idi, leaveTimei] where: idi is the id of the employee that worked on the ith task, and leaveTimei is the time at which the employee finished the ith task. All the values leaveTimei are unique. Note that the ith task starts the..

문제) 1026. Maximum Difference Between Node and Ancestor 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,null,null,4,7,13] Output: 7 Expla..