Python
Searching Algorithms
Linear search checks everything; binary search halves the problem each step. Knowing when the second is possible is worth more than either implementat...
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Python
Sorting Algorithms
Python sorts for you in n log n. Implementing bubble, insertion, merge and quick sort is still worth doing, because it teaches how algorithms are comp...
Python
Stacks, Queues and Linked Lists
Three linear structures defined by where you may add and remove items. Python gives you two of them almost for free; the third is worth building once.
Python
Hashing and Frequency Counting
A dictionary turns "have I seen this?" and "how many of these?" from an O(n) scan into an O(1) lookup. That single change solves a large share of inte...
Python
Two Pointers and Sliding Window
Two techniques that turn a nested loop into a single pass. Two pointers move towards each other; a sliding window grows and shrinks over a range.
Python
Trees and Graphs
A tree is a graph with no cycles and one root. Both are walked with the same two strategies - depth first with a stack, breadth first with a queue.
HTML
What is HTML: The Structure Layer of Every Web Page
HTML is a markup language, not a programming language. It labels content so that browsers, search engines and assistive technology all agree on what e...
HTML
HTML Document Structure: DOCTYPE, html, head and body
Every page is built from the same four parts. Learn what the doctype actually does, why html carries the lang attribute, and the rule that decides whe...
HTML
Elements, Tags and Attributes: The Vocabulary of HTML
Tag, element and attribute are three different things, and interviews test the difference constantly. Learn the anatomy, the void elements, boolean at...
HTML
HTML Comments: Notes That Ship With Your Code
Comments explain markup to the next developer, but they are downloaded by every visitor and readable by anyone. Learn the syntax, the nesting trap and...
HTML
Block Level and Inline Elements
The oldest distinction in HTML layout: block boxes stack down the page and fill the width, inline boxes sit inside a line of text. It also decides whi...
HTML
Writing and Running Your First HTML Page
Set up a folder, save a real .html file, open it in a browser and understand the difference between opening a file and serving it. The workflow every...