Algorithm for finding nearest object on 2D grid

Question

Say you have a 2D grid with each spot on the grid having x number of objects (with x >=0). I am having trouble thinking of a clean algorithm so that when a user speci

Answer 1

If your objects are dense, then just searching the nearby points will probably be the best way to find the nearest object, spiraling out from the center. If your objects are sparse, then a quadtree or related data structure (R-tree, etc.) is probably better. Here is a writeup with examples.

I do not know of a good online algorithm reference, but I can say that if you are going to write more than the occasional line of code, saving your pennies to buy CLRS will be worth the money. There are lectures based on this book online that have been painstakingly annotated by Peteris Krumins, but they only cover part of the book. This is one of the few books that you need to own.