.Zzumbong

난이도 [ 🤔 ] Medium 문제 설명 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. 문자열 s에 문자가 등장횟수만큼 내림차순 정렬한다. aaaccc, cccaaa 는 둘다 정답이란다. 숫자만 신경쓰면 된다. 입출력 예 Example 1: Input: s = "tree" Output: "eert" Explanation: ..

난이도 [ 🤔 ] Medium 문제 설명 Two strings are considered close if you can attain one from the other using the following operations: Operation 1: Swap any two existing characters. For example, abcde -> aecdb Operation 2: Transform every occurrence of one existing character into another existing character, and do the same with the other character. For example, aacabb -> bbcbaa (all a's turn into b's, and..

난이도 [ 😊 ] Easy 문제 설명 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. Otherwise, return false. 짝수 ..

난이도 [ 😊 ] Easy 문제 설명 Given an array of integers arr, return true if the number of occurrences of each value in the array is unique, or false otherwise. int 로 이루어진 arr가 있다. 여기에 나오는 숫자가 발생횟수가 유니크 할때 true이다. 입출력 예 Example 1: Input: arr = [1,2,2,1,1,3] Output: true Explanation: The value 1 has 3 occurrences, 2 has 2 and 3 has 1. No two values have the same number of occurrences. 1은 3번, 2는 2번, 3은 1번 ..

난이도 [ 🤔 ] Medium 문제 설명 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() Returns a random ele..

문제 설명 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 should be returned in increasing order. Note:..

문제 설명 Given an integer array nums, return the number of all the arithmetic subsequences of nums. A sequence of numbers is called arithmetic if it consists of at least three elements and if the difference between any two consecutive elements is the same. For example, [1, 3, 5, 7, 9], [7, 7, 7, 7], and [3, -1, -5, -9] are arithmetic sequences. For example, [1, 1, 2, 5, 7] is not an arithmetic sequ..

문제 설명 Given an array of integers arr, find the sum of min(b), where b ranges over every (contiguous) subarray of arr. Since the answer may be large, return the answer modulo 109 + 7. 정수 배열에서 min(b)의 합을 구하는데, b는 arr의 모든 연속된 하위 배열이란다. 예제를 보면 이해하 간다. 숫자가 크니까 modulo로 나머지를 리턴하란다. 입출력 예 Example 1: Input: arr = [3,1,2,4] Output: 17 Explanation: Subarrays are [3], [1], [2], [4], [3,1], [1,2], [2,4], [3,..

문제 설명 Given an m x n grid of characters board and a string word, return true if word exists in the grid. The word can be constructed from letters of sequentially adjacent cells, where adjacent cells are horizontally or vertically neighboring. The same letter cell may not be used more than once. m x n 문자열 그리드 board가 주어지고, 이 board에 word가 있다면 true를 return 한다. 단어는 가로 세로로 붙어있어야하고 한번 사용한 글자 칸은 두 번이상 사..

문제 설명 Given a string s, you can transform every letter individually to be lowercase or uppercase to create another string. Return a list of all possible strings we could create. Return the output in any order. String s 를 받아서 개별적으로 소문자나 대문자로 변환하여, 만들 수 있는 모든 문자열을 Array로 반환한다. 순서는 상관없다. 입출력 예 Example 1: Input: s = "a1b2" Output: ["a1b2","a1B2","A1b2","A1B2"] Example 2: Input: s = "3z4" Output: ["3..

문제 설명 A triplet is an array of three integers. You are given a 2D integer array triplets, where triplets[i] = [ai, bi, ci] describes the ith triplet. You are also given an integer array target = [x, y, z] that describes the triplet you want to obtain. To obtain target, you may apply the following operation on triplets any number of times (possibly zero): Choose two indices (0-indexed) i and j (i..

문제 설명 Write a function to find the longest common prefix string amongst an array of strings. If there is no common prefix, return an empty string "". 문자열 배열 중에 가장 긴 공통 접두사를 찾는 문제, 없으면 ''을 리턴 입출력 예 Example 1: Input: strs = ["flower","flow","flight"] Output: "fl" Example 2: Input: strs = ["dog","racecar","car"] Output: "" Explanation: There is no common prefix among the input strings. Constraints 1

문제 설명 You are given an m x n matrix maze (0-indexed) with empty cells (represented as '.') and walls (represented as '+'). You are also given the entrance of the maze, where entrance = [entrancerow, entrancecol] denotes the row and column of the cell you are initially standing at. In one step, you can move one cell up, down, left, or right. You cannot step into a cell with a wall, and you cannot..

문제 설명 Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order. 입출력 예 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

문제 설명 Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. For example, 2 is written as II in Roman numeral, just two ones added together. 12 is written as XII, which is simply X + II. The number 27 is written as XXVII, which is XX + V + II. Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not IIII. Instead,..

문제 설명 Given a string s, return the longest palindromic substring in s. palindromic: A string is palindromic if it reads the same forward and backward. 입출력 예 Example 1: Input: s = "babad" Output: "bab" Explanation: "aba" is also a valid answer. Example 2: Input: s = "cbbd" Output: "bb" Constraints 1 0; i--) { for(let j = 0; j answer.length){ const word = s.slice(j, i); ..

문제 설명 Given a string s representing a valid expression, implement a basic calculator to evaluate it, and return the result of the evaluation. Note: You are not allowed to use any built-in function which evaluates strings as mathematical expressions, such as eval(). 입출력 예 Example 1: Input: s = "1 + 1" Output: 2 Example 2: Input: s = " 2-1 + 2 " Output: 3 Example 3: Input: s = "(1+(4+5+2)-3)+(6+8)..

문제 설명 A sentence consists of lowercase letters ('a' to 'z'), digits ('0' to '9'), hyphens ('-'), punctuation marks ('!', '.', and ','), and spaces (' ') only. Each sentence can be broken down into one or more tokens separated by one or more spaces ' '. A token is a valid word if all three of the following are true: It only contains lowercase letters, hyphens, and/or punctuation (no digits). Ther..

문제 설명 Given an integer x, return true if x is a palindrome, and false otherwise. palindrome : An integer is a palindrome when it reads the same forward and backward. For example, 121 is a palindrome while 123 is not. 입출력 예 Example 1: Input: x = 121 Output: true Explanation: 121 reads as 121 from left to right and from right to left. Example 2: Input: x = -121 Output: false Explanation: From left..

문제 설명 Determine if a 9 x 9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules: Each row must contain the digits 1-9 without repetition. Each column must contain the digits 1-9 without repetition. Each of the nine 3 x 3 sub-boxes of the grid must contain the digits 1-9 without repetition. Note: A Sudoku board (partially filled) could be valid but is..