[Blind75] Best time to buy and sell stock

121. Best Time to Buy and Sell Stock #Array #Dynamic Programming #blind75/2 problem You are given an array prices where prices[i] is the price of a given stock on the ith day. You want to maximize your profit by choosing a single day to buy one stock and

[Blind75] Two Sum

1. Two Sum #Array #Hash_table #blind75/1 problem Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target. You may assume that each input would have exactly one solution, and you may not use the same

LeetCode 2073 solution

2073. Time Needed to Buy Tickets #Easy #Queue problem There are n people in a line queuing to buy tickets, where the 0th person is at the front of the line and the (n - 1)th person is at the back of the line. You are given a 0-indexed

LeetCode 1700 solution

1700. Number of Students Unable to Eat Lunch #Easy #Queue problem The school cafeteria offers circular and square sandwiches at lunch break, referred to by numbers 0 and 1 respectively. All students stand in a queue. Each student either prefers square or circular sandwiches. The number of sandwiches in the

LeetCode 678 solution

678. Valid Parenthesis String #Medium #stack #dp problem Given a string s containing only three types of characters: '(', ')' and '*', return true if s is valid. The following rules define a valid string: * Any left parenthesis '(' must have a corresponding right parenthesis '

LeetCode 1249 solution

1249. Minimum Remove to Make Valid Parentheses #Medium #stack problem Given a string s of '(' , ')' and lowercase English characters. Your task is to remove the minimum number of parentheses ('(' or ')', in any positions) so that the resulting parentheses string is valid and

LeetCode 1544 solution

1544. Make The String Great #Easy #Stack problem Given a string s of lower and upper case English letters. A good string is a string which doesn't have two adjacent characters s[i] and s[i + 1] where: * 0 <= i <= s.length - 2 * s[i]

LeetCode 1614 solution

1614. Maximum Nesting Depth of the Parentheses #Easy #Stack problem A string is a valid parentheses string (denoted VPS) if it meets one of the following: * It is an empty string "", or a single character not equal to "(" or ")", * It can be written as

LeetCode 205 solution

205. Isomorphic Strings #Hash_table #String problem Given two strings s and t, determine if they are isomorphic. Two strings s and t are isomorphic if the characters in s can be replaced to get t. All occurrences of a character must be replaced with another character while preserving the

LeetCode 58 solution

58. Length of Last WordSolved #Easy #String problem Given a string s consisting of words and spaces, return the length of the last word in the string. A word is a maximal  substring consisting of non-space characters only. Example 1: * Input: s = "Hello World" * Output: 5 * Explanation: The

Python String method

가끔 알고리즘을 풀다 보면 string method를 필요로 할 경우들이 있다. 아주 쉬운 문제인 경우는 string method를 이용하면 순식간에 풀 수 있다. 하지만 기억이 가물가물할 경우에는 한참을 돌아가야 한다. 때문에 이에 대해서 document를 보면서 정리한다.

LeetCode 2958 solution

2958. Length of Longest Subarray With at Most K Frequency #Medium #Array #Hash_table #Sliding_window problem You are given an integer array nums and an integer k. The frequency of an element x is the number of times it occurs in an array. An array is called good if

LeetCode 713 solution

713. Subarray Product Less Than K #Medium #Array #SlidingWindow problem Given an array of integers nums and an integer k, return the number of contiguous subarrays where the product of all the elements in the subarray is strictly less than k. Example 1: * Input: nums = [10,5,2,6], k

LeetCode 442 solution

442.  Find All Duplicates in an Array #Array #HashTable problem Given an integer array nums of length n where all the integers of nums are in the range [1, n] and each integer appears once or twice, return an array of all the integers that appears twice. You must write

LeetCode 1609 solution

1609. Even Odd Tree #Tree #Breadth-First Search #Binary Tree problem A binary tree is named Even-Odd if it meets the following conditions: - The root of the binary tree is at level index 0, its children are at level index 1, their children are at level index 2, etc. -

DeBERTa

DECODING-ENHANCED BERT WITH DIS-ENTANGLED ATTENTION Arxiv Abstract Recent progress in pre-trained neural language models has significantly improved the performance of many natural language processing (NLP) tasks. In this paper we propose a new model architecture DeBERTa (Decoding-enhanced BERT with disentangled attention) that improves the BERT and RoBERTa models using two

Session

session이란 client로부터 오는 일련의 Request를 하나의 status로 보고, 그 status를 일정하게 유지하는 기술을 말한다. 다시 말하면 client가 web server에 접속해있는 상태 를 하나의 세션으로 보는 것이다. 브라우저를 닫거나, 서버에서 세션을 삭제하면 세션이 끊기고 없어진다. 세션은 각 클라이언트의 고유 세션id를 부여하는데, 이것으로 각 클라이언트를 구분하여 각 클라이언트의 요구에 맞는 응답을 반환한다.

Algorithm

LeetCode 513 solution

513. Find Bottom Left Tree Value #Medium #Binary_tree problem Given the root of a binary tree, return the leftmost value in the last row of the tree. python # Definition for a binary tree node. # class TreeNode: # def __init__(self, val=0, left=None, right=None): # self.val = val # self.

MLDL

Linear Regressin & Gradient Descent

Hypothesis function 가설 함수 Hypothesis Definition To Describe the supervised learning problem slightly more formally, our goal is, given a training set, to learn a function $h : X \mapsto Y$ that $h(x)$ is a "good" predictor for the corresponding value of $y$. For historical reasons, this function

Algorithm

LeetCode 543 solution

543. Diameter of Binary Tree #Binary_Tree problem Given the root of a binary tree, return the length of the diameter of the tree. The diameter of a binary tree is the length of the longest path between any two nodes in a tree. This path may or may not

Algorithm

LeetCode 387 solution

387. First Unique Character in a String #hash_table problem Given a string s, find the first non-repeating character in it and return its index. If it does not exist, return -1.   Example 1: Input: s = "leetcode" Output: 0 Example 2: Input: s = "loveleetcode" Output: 2

Algorithm

LeetCode 1207 solution

1207. Unique Number of Occurrences #Easy #Array #HashTable Problem URL problem Given an array of integers arr, return true if the number of occurrences of each value in the array is unique or false otherwise. Example 1: * Input: arr = [1,2,2,1,1,3] * Output: true * Explanation: The value

Algorithm

LeetCode 2385 solution

2385. Amount of Time for Binary Tree to be Infected #Medium #BFS #DFS #Binary Tree problem You are given the root of a binary tree with unique values, and an integer start. At minute 0, an infection starts from the node with value start. Each minute, a node becomes infected

desing pattern

MVC pattern

위 그림은 소프트웨어 아키텍처에서 Model-View-Controller (MVC) 패턴을 나타냅니다. MVC 패턴은 주로 웹 애플리케이션 개발에 사용되며, 애플리케이션의 구조를 세 가지 주요 구성 요소로 나눕니다: 모델(Model), 뷰(View), 컨트롤러(Controller). 1. 모델(Model): 데이터 레이어를 나타냅니다. 이는 애플리케이션의 데이터와 비즈니스 로직을 포함하며, 데이터베이스와의 상호작용을 관리합니다. 2. 뷰(View): 사용자 인터페이스(UI)

Algorithm

LeetCode 872 Solution

Problem Consider all the leaves of a binary tree, from left to right order, the values of those leaves form a leaf value sequence. For example, in the given tree above, the leaf value sequence is (6, 7, 4, 9, 8). Two binary trees are considered leaf-similar if their leaf

java

LocalDate, LocalTime, LocalDateTime

LocalDate LocalDate (Java Platform SE 8 ) Java의 LocalDate 클래스는 날짜를 표현하기 위해 사용되는 클래스입니다. 이 클래스는 Java 8 이상에서 사용 가능한 java.time 패키지의 일부입니다. LocalDate는 시간대를 고려하지 않는 순수한 날짜(년, 월, 일)를 나타냅니다. 여기에는 시간, 분, 초 등의 시간 정보는 포함되어 있지 않습니다. java.time.LocalDate를 import하면

LeetCode 938 Solution

Problem Given the root node of a binary search tree and two integers low and high, return the sum of values of all nodes with a value in the inclusive range [low, high]. Example 1: * Input: root = [10,5,15,3,7,null,18], low = 7, high = 15 * Output: 32

Leetcode 2879 Solution

2870. Minimum number of Operations to make Array Empty #Medium #Hash #Quotient_remain You are given a 0-indexed array nums consisting of positive integers. There are two types of operations that you can apply on the array any number of times: Choose two elements with equal values and delete them

LeetCode 2125 solution

2125. Number of Laser Beams in a Bank # Medium # Array # Matrix Anti-theft security devices are activated inside a bank. You are given a 0-indexed binary string array bank representing the floor plan of the bank, which is an m x n 2D matrix. bank[i] represents the ith row, consisting

Algorithm

LeetCode 1335 solution

1335. Minimum Difficulty of a Job Schedule #Hard Problem URL You want to schedule a list of jobs in d days. Jobs are dependent (i.e To work on the ith job, you have to finish all the jobs j where 0 <= j < i). You have to finish

LeetCode 1531 Solution

1531. String Compression #Hard # Run-length encoding is a string compression method that works by replacing consecutive identical characters (repeated 2 or more times) with the concatenation of the character and the number marking the count of the characters (length of the run). For example, to compress the string "aabccc&

Algorithm

LeetCode 724 solution

724. Find Pivot Index #Easy #Cumulative_sum Given an array of integers nums, calculate the pivot index of this array. The pivot index is the index where the sum of all the numbers strictly to the left of the index is equal to the sum of all the numbers strictly