Easy

Given a URL startUrl and an interface HtmlParser, implement a Multi-threaded web crawler to crawl all links that are under the same hostname as startUrl. Return all URLs obtained by your web crawler in any order. Your crawler should: Start from the page: startUrl Call HtmlParser.getUrls(url) to get all URLs from a webpage of a given URL. Do not crawl the same link twice. Explore only the links that are under the same hostname as startUrl. As shown in the example URL above, the hostname is example.org. For simplicity’s sake, you may assume all URLs use HTTP protocol without any port specified. For example, the URLs http://leetcode.com/problems and http://leetcode.com/contest are under the same hostname, while URLs http://example.org/test and http://example.com/abc are not under the same hostname. ...

Given an integer array sorted in non-decreasing order, there is exactly one integer in the array that occurs more than 25% of the time, return that integer. 1 2 3 4 5 6 7 8 9 Example 1: Input: arr = [1,2,2,6,6,6,6,7,10] Output: 6 Example 2: Input: arr = [1,1] Output: 1 Constraints: ...

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 choosing a different day in the future to sell that stock. Return the maximum profit you can achieve from this transaction. If you cannot achieve any profit, return 0. ...

Given two non-negative integers, num1 and num2 represented as string, return the sum of num1 and num2 as a string. You must solve the problem without using any built-in library for handling large integers (such as BigInteger). You must also not convert the inputs to integers directly. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Example 1: Input: num1 = "11", num2 = "123" Output: "134" Example 2: Input: num1 = "456", num2 = "77" Output: "533" Example 3: Input: num1 = "0", num2 = "0" Output: "0" Constraints: ...

Given two string arrays word1 and word2, return true if the two arrays represent the same string, and false otherwise. A string is represented by an array if the array elements concatenated in order forms the string. 1 2 3 4 5 6 7 8 Example 1: Input: word1 = ["ab", "c"], word2 = ["a", "bc"] Output: true Explanation: word1 represents string "ab" + "c" -> "abc" word2 represents string "a" + "bc" -> "abc" The strings are the same, so return true. 1 2 3 4 Example 2: Input: word1 = ["a", "cb"], word2 = ["ab", "c"] Output: false 1 2 3 4 Example 3: Input: word1 = ["abc", "d", "defg"], word2 = ["abcddefg"] Output: true Constraints: ...

1360. Number of Days Between Two Dates Write a program to count the number of days between two dates. The two dates are given as strings, their format is YYYY-MM-DD as shown in the examples. 1 2 3 4 5 6 7 8 9 Example 1: Input: date1 = "2019-06-29", date2 = "2019-06-30" Output: 1 Example 2: Input: date1 = "2020-01-15", date2 = "2019-12-31" Output: 15 Constraints: ...

1528. Shuffle String A city’s skyline is the outer contour of the silhouette formed by all the buildings in that city when viewed from a distance. Given the locations and heights of all the buildings, return the skyline formed by these buildings collectively. The geometric information of each building is given in the array buildings where buildings[i] = [lefti, righti, heighti]: lefti is the x coordinate of the left edge of the ith building. righti is the x coordinate of the right edge of the ith building. heighti is the height of the ith building. You may assume all buildings are perfect rectangles grounded on an absolutely flat surface at height 0. ...

1266. Minimum Time Visiting All Points On a 2D plane, there are n points with integer coordinates points[i] = [xi, yi]. Return the minimum time in seconds to visit all the points in the order given by points. You can move according to these rules: In 1 second, you can either: move vertically by one unit, move horizontally by one unit, or move diagonally sqrt(2) units (in other words, move one unit vertically then one unit horizontally in 1 second). You have to visit the points in the same order as they appear in the array. You are allowed to pass through points that appear later in the order, but these do not count as visits. 1 2 3 4 5 6 7 8 Example 1: Input: points = [[1,1],[3,4],[-1,0]] Output: 7 Explanation: One optimal path is [1,1] -> [2,2] -> [3,3] -> [3,4] -> [2,3] -> [1,2] -> [0,1] -> [-1,0] Time from [1,1] to [3,4] = 3 seconds Time from [3,4] to [-1,0] = 4 seconds Total time = 7 seconds 1 2 3 4 Example 2: Input: points = [[3,2],[-2,2]] Output: 5 Constraints: ...

270. Closest Binary Search Tree Value Given the root of a binary search tree and a target value, return the value in the BST that is closest to the target. 1 2 3 4 Example 1: Input: root = [4,2,5,1,3], target = 3.714286 Output: 4 1 2 3 4 Example 2: Input: root = [1], target = 4.428571 Output: 1 Constraints: ...

252. Meeting Rooms Given an array of meeting time intervals where intervals[i] = [starti, endi], determine if a person could attend all meetings. 1 2 3 4 5 6 7 8 9 Example 1: Input: intervals = [[0,30],[5,10],[15,20]] Output: false Example 2: Input: intervals = [[7,10],[2,4]] Output: true Constraints: ...