Tutorial by Examples: s

The above forest methodology is actually a disjoint-set data structure, which involves three main operations: subalgo makeSet(v: a node): v.parent = v <- make a new tree rooted at v subalgo findSet(v: a node): if v.parent == v: return v return findSet(v.parent...

We can do two things to improve the simple and sub-optimal disjoint-set subalgorithms: Path compression heuristic: findSet does not need to ever handle a tree with height bigger than 2. If it ends up iterating such a tree, it can link the lower nodes directly to the root, optimizing future trav...

Sort the edges by value and add each one to the MST in sorted order, if it doesn't create a cycle. algorithm kruskalMST(G: a graph) sort G's edges by their value MST = an empty graph for each edge e in G: if adding e to MST does not create a cycle: add e to MST ...

The DOM (Document Object Model) is the programming interface for HTML and XML documents, it defines the logical structure of documents and the way a document is accessed and manipulated. The main implementers of the DOM API are web browsers. Specifications are standardized by the W3C and the WHATW...

You can calculate a number in the Fibonacci sequence using recursion. Following the math theory of F(n) = F(n-2) + F(n-1), for any i > 0, // Returns the i'th Fibonacci number public int fib(int i) { if(i <= 2) { // Base case of the recursive function. // i is either 1...

JSON stands for "JavaScript Object Notation", but it's not JavaScript. Think of it as just a data serialization format that happens to be directly usable as a JavaScript literal. However, it is not advisable to directly run (i.e. through eval()) JSON that is fetched from an external source...

1. Target a device by serial number Use the -s option followed by a device name to select on which device the adb command should run. The -s options should be first in line, before the command. adb -s <device> <command> Example: adb devices List of devices attached emulator-55...

Each requirements files should match the name of a settings files. Read Using multiple settings for more information. Structure djangoproject ├── config │ ├── __init__.py │ ├── requirements │ │ ├── base.txt │ │ ├── dev.txt │ │ ├── test.txt │ │ └── prod.txt │ └── setti...

' This method is useful for iterating Enum values ' Enum Animal Dog = 1 Cat = 2 Frog = 4 End Enum Dim Animals = [Enum].GetValues(GetType(Animal)) For Each animal in Animals Console.WriteLine(animal) Next Prints: 1 2 4

using (new Sitecore.SecurityModel.SecurityDisabler()) { var item = Sitecore.Context.Database.GetItem("/sitecore/content/home"); }

var user = Sitecore.Security.Accounts.User.FromName("sitecore/testname", false); using (new Sitecore.Security.Accounts.UserSwitcher(user)) { var item = Sitecore.Context.Database.GetItem("/sitecore/content/home"); }

NSError *e = nil; NSString *jsonString = @"[{\"id\": \"1\", \"name\":\"sam\"}]"; NSData *data = [jsonString dataUsingEncoding:NSUTF8StringEncoding]; NSArray *jsonArray = [NSJSONSerialization JSONObjectWithData: data options: NSJSONReadingMutabl...

Useful if your program is outputting web pages along the way. from http.server import HTTPServer, CGIHTTPRequestHandler import webbrowser import threading def start_server(path, port=8000): '''Start a simple webserver serving path on port''' os.chdir(path) httpd = HTTPServer((''...

When you create an argparse ArgumentParser() and run your program with '-h' you get an automated usage message explaining what arguments you can run your software with. By default, positional arguments and conditional arguments are separated into two categories, for example, here is a small script ...

Use associated type when there is a one-to-one relationship between the type implementing the trait and the associated type. It is sometimes also known as the output type, since this is an item given to a type when we apply a trait to it. Creation trait GetItems { type First; // ^~~~ d...

Use the maxlen parameter while creating a deque to limit the size of the deque: from collections import deque d = deque(maxlen=3) # only holds 3 items d.append(1) # deque([1]) d.append(2) # deque([1, 2]) d.append(3) # deque([1, 2, 3]) d.append(4) # deque([2, 3, 4]) (1 is removed because i...

Creating empty deque: dl = deque() # deque([]) creating empty deque Creating deque with some elements: dl = deque([1, 2, 3, 4]) # deque([1, 2, 3, 4]) Adding element to deque: dl.append(5) # deque([1, 2, 3, 4, 5]) Adding element left side of deque: dl.appendleft(0) # deque([0, 1, 2, ...

A basic User Schema: var mongoose = require('mongoose'); var userSchema = new mongoose.Schema({ name: String, password: String, age: Number, created: {type: Date, default: Date.now} }); var User = mongoose.model('User', userSchema); Schema Types.

Methods can be set on Schemas to help doing things related to that schema(s), and keeping them well organized. userSchema.methods.normalize = function() { this.name = this.name.toLowerCase(); }; Example usage: erik = new User({ 'name': 'Erik', 'password': 'pass' }); erik.nor...

Often times you will see an exception Anti forgery token is meant for user "" but the current user is "username" This is because the Anti-Forgery token is also linked to the current logged-in user. This error appears when a user logs in but their token is still linked to bein...