Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it can trap after raining.
A chef has collected data on the satisfaction level of his n dishes. Chef can cook any dish in 1 unit of time.
Like-time coefficient of a dish is defined as the time taken to cook that dish including previous dishes multiplied by its satisfaction level i.e. time[i]*satisfaction[i]
Return the maximum sum of Like-time coefficient that the chef can obtain after dishes preparation.
Dishes can be prepared in any order and the chef can discard some dishes to get this maximum value.
1063. Number of Valid Subarrays
Given an array nums of integers, return the number of non-empty continuous subarrays that satisfy the following condition:
The leftmost element of the subarray is not larger than other elements in the subarray.
The n-queens puzzle is the problem of placing n queens on an n x n chessboard such that no two queens attack each other.
Given an integer n, return the number of distinct solutions to the n-queens puzzle.
The n-queens puzzle is the problem of placing n queens on an n x n chessboard such that no two queens attack each other.
Given an integer n, return all distinct solutions to the n-queens puzzle. You may return the answer in any order.
Each solution contains a distinct board configuration of the n-queens’ placement, where ‘Q’ and ‘.’ both indicate a queen and an empty space, respectively.
1242. Web Crawler Multithreaded
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 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 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.
The HtmlParser interface is defined as such:
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// Return a list of all urls from a webpage of given url.
// This is a blocking call, that means it will do HTTP request and return when this request is finished.
public List<String> getUrls(String url);
}Note that getUrls(String url) simulates performing a HTTP request. You can treat it as a blocking function call which waits for a HTTP request to finish. It is guaranteed that getUrls(String url) will return the urls within 15ms. Single-threaded solutions will exceed the time limit so, can your multi-threaded web crawler do better?
Below are two examples explaining the functionality of the problem, for custom testing purposes you’ll have three variables urls, edges and startUrl. Notice that you will only have access to startUrl in your code, while urls and edges are not directly accessible to you in code.
Follow up:
- Assume we have 10,000 nodes and 1 billion URLs to crawl. We will deploy the same software onto each node. The software can know about all the nodes. We have to minimize communication between machines and make sure each node does equal amount of work. How would your web crawler design change?
- What if one node fails or does not work?
- How do you know when the crawler is done?
