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C#'s generic collections already hold most of this path: Stack<T>, Queue<T>, Dictionary<TKey,TValue>, LinkedList<T> and SortedSet<T> are a stack, a queue, a hash table, a doubly linked list and a balanced search tree. Build each structure yourself in C#, then sort, recurse and search graphs with them, and finish on graded interview problems. Free, in your browser, with a certificate on most courses.
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23 free certificates along the pathEach step is a set of existing Coddy courses, and every Start button opens them in C#. The three courses not taught in C# yet are listed after the steps.
Stack<T>, Queue<T> and Dictionary<TKey,TValue> are structures you have written, and you know what each of their calls costs.StartLinkedList<T> is the first of them, ready-made; after this step SortedSet<T> is a balanced tree you understand, red-black where yours is AVL, and a heap is something you can write on any .NET version.StartArray.Sort and List<T>.Sort are an introsort, quicksort backed by heapsort and insertion sort, and unstable, while LINQ's OrderBy is stable; after this step you know why.StartStackOverflowException, which cannot be caught, so every recursive method needs its way out before it needs anything else. Dynamic programming and bit manipulation are listed after the steps, since they are taught in Python and C++.StartDedicated pageWrite real code, query databases, build websites, and master AI prompts. Our interactive lessons cover every skill modern developers need.
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Double or Nothing
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Promotion zoneRead, listen, test yourself, ask the AI, or look up anything you've already covered. Every lesson meets you where you are.
A variable is a named container that stores a value you can reference later in your program.
In Python, you create one by writing the name, an equals sign, then the value you want to store.
The value can change over time - reassigning the name simply points it to a new value.
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Certificate of CompletionPython Fundamentals
Add to LinkedInList<T> is a dynamic array, so Insert(0, x) shifts every element behind it; Dictionary<TKey,TValue> is a hash table, constant time on average and only as good as your keys' GetHashCode. Building the structures yourself is how those facts stop being trivia and start deciding which collection you pick.System.Collections.Generic covers most of the structures on this path. Two habits are worth building early. LINQ is concise, but every OrderBy is a sort and every Where a loop, so it hides the costs you are learning to count; and Array.Sort is unstable, which matters whenever equal keys must keep their order.List<T> is a dynamic array, Stack<T> and Queue<T> are array-backed, LinkedList<T> is a doubly linked list, Dictionary<TKey,TValue> and HashSet<T> are hash tables, and SortedDictionary<TKey,TValue> and SortedSet<T> are red-black trees, balanced like the AVL tree you build in step two. SortedList<TKey,TValue> is a pair of arrays kept in key order, and since .NET 6 PriorityQueue<TElement,TPriority> is an array-backed min-heap. There is no trie or graph class; those you write yourself.struct is a value type: it cannot contain a field of its own type at all, and wherever it is copied, a change to the copy leaves the original untouched. A class instance is a reference, so nodes can point at each other the way a linked list or a tree needs. Keep structs for small values, such as a grid coordinate or a weighted edge.PriorityQueue<TElement,TPriority>, an array-backed min-heap in which every element is enqueued with its own priority; pass an IComparer<TPriority> that reverses the order to get a max-heap. .NET Framework and older runtimes have none, which is why C# developers long wrote their own heap or bent a SortedSet<T> into one, and why being able to write one still matters. Step two is where you do.Dictionary, and bit tricks port cleanly, down to the distinction C++ draws: >> keeps the sign on an int and fills with zeros on a uint.List<T>, at least. If those are new, Coddy's C# course takes you there first, free, and this path picks up where it ends.