Avoid O(n^2) complexity for collision detection

Question

I am developing a simple tile-based 2D game. I have a level, populated with objects that can interact with the tiles and with each other. Checking collision with the tilemap

Answer 1

You can use quadtree to divide the space and reduce the number of objects you need to check for collision.

See this article - Quadtree demonstration.

And perhaps this - Collision Detection in Two Dimensions.

Or this - Quadtree (source included)

It may seem - at first glance - that it takes a lot of CPU power to maintain the tree, but it also reduces the number of checks significantly (see the demonstration in th first link).