Many algorithms will specify that duplicates are excluded. For example, the example algorithms in the MIT Algorithms book usually present examples without duplicates. It is fairly trivial to implement duplicates (either as a list at the node, or in one particular direction.) Most (that I’ve seen) specify left children as <= and right children as … Read more
Consider a data structure composed of a hashtable H and an array A. The hashtable keys are the elements in the data structure, and the values are their positions in the array. insert(value): append the value to array and let i be its index in A. Set H[value]=i. remove(value): We are going to replace the … Read more
Binary tree: Tree where each node has up to two leaves 1 / \ 2 3 Binary search tree: Used for searching. A binary tree where the left child contains only nodes with values less than the parent node, and where the right child only contains nodes with values greater than or equal to the … Read more
One advantage that no one else has pointed out is that binary search tree allows you to do range searches efficiently. In order to illustrate my idea, I want to make an extreme case. Say you want to get all the elements whose keys are between 0 to 5000. And actually there is only one … Read more
Your quadtree structure isn’t optimal. You’re right to store 4 subtrees per node, but actual objects should only be stored inside the leaves, not inner nodes. Therefore the collection holding the actual objects needs to be moved to the leaves. Let’s have a look at the implementation of the operations: Insert an object into the … Read more
There are at least 4 libraries that I am aware of providing lenses. The notion of a lens is that it provides something isomorphic to data Lens a b = Lens (a -> b) (b -> a -> a) providing two functions: a getter, and a setter get (Lens g _) = g put (Lens … Read more
Modeling graph-like structures in Rust is not a simple problem. Here there are two valuable discussions from Nick Cameron and Niko Matsakis (two main Rust developers at Mozilla.) Graphs and arena allocation Modeling Graphs in Rust Using Vector Indices
Rust tries to ensure memory safety by forbidding you from doing things that might potentially be unsafe. Since this analysis is performed at compile-time, the compiler can only reason about a subset of manipulations that are known to be safe. In Rust, you could easily store either a reference to the parent (by borrowing the … Read more
Here’s an explanation in layman’s terms. Let’s assume you want to fill up a library with books and not just stuff them in there, but you want to be able to easily find them again when you need them. So, you decide that if the person that wants to read a book knows the title … Read more