computer-science

This is more of a CS question, but an interesting one : Let's say we have 2 tree structures with more or less the same nodes reorganized. How would you find any in some sense minimal sequence of operations MOVE(A, B) - moves node A under node B (with the whole subtree) INSERT(N, B) - inserts a new node N under node B DELETE (A) - deletes the node A (with the whole subtree) that transforms one tree to the other. There might obviously be cases where such transformation is not possible, trivial being root A with child B to root B with child A etc.). In such cases, the algorithm would simply

Given let doAsynchronousStuff = () => { return new Promise(resolve => { setTimeout(() => { resolve("abcdefg"[Math.floor(Math.random() * 7)]) }, Math.PI * 1 + Math.random()) }) .then(data => console.log(data)) .then(doAsynchronousStuff) } Is the pattern an implementation of recursion; tail-call optimization; iteration; a non-terminating procedure that happens to refer to itself; or; other common pattern that is not listed above? Looking for an answer drawing from credible and/or official sources. I rewrote the code eliminating all non relevant stuff and using a style I feel is more readable and

In a CS course I'm taking there is an example of a language that is not regular: {a^nb^n | n >= 0} I can understand that it is not regular since no Finite State Automaton/Machine can be written that validates and accepts this input since it lacks a memory component. (Please correct me if I'm wrong) The wikipedia entry on Regular Language also lists this example, but does not provide a (mathematical) proof why it is not regular. Can anyone enlighten me on this and provide proof for this, or point me too a good resource? cletus What you're looking for is Pumping lemma for regular languages .

I'm atttempting to find the non-zero (x,y) coordinates of a binary image. I've found a few references to the function countNonZero() which only counts the non-zero coordinates and findNonZero() which I'm unsure how to access or use since it seems to have been removed from the documentation completely. This is the closest reference I found, but still not helpful at all. I would appreciate any specific help. Edit: - To specify, this is using C++ WangYudong Here is an explanation for how findNonZero() saves non-zero elements. The following codes should be useful to access non-zero coordinates of

I have a simple class: public class TileName { int Zoom, X, Y; public override bool Equals (object obj) { var o = obj as TileName; return (o != null) && (o.Zoom == Zoom) && (o.X == X) && (o.Y == Y); } public override int GetHashCode () { return (Zoom + X + Y).GetHashCode(); } } I was curious if I would get a better distribution of hash codes if I instead did something like: public override int GetHashCode () { return Zoom.GetHashCode() + X.GetHashCode() + Y.GetHashCode(); } This class is going to be used as a Dictionary key, so I do want to make sure there is a decent distribution. Philip