Simple algorithm for generating random numbers with bigger smaller probability

Question

I'm currently working on a game, with scrollable screen and I need to find a simple algorithm for placing obstacles in the game. I have a gameSpeed, that is increased in time (from 1 to 12, increased by 0.005 each 1/60s) and a range of available positions between 200 and 600 (ints). I'd like to achieve a bigger probability of receiving smaller number when the speed is bigger, but it's my 14th hour straight coding and I cannot come up with anything usable and not overcomplicated. I'd like to minimize Math and random functions so that the rendering loop won't take too long. Any help appreciated !

Answer 1

To move the density in one way, you may square or square-root the random number. Math.random()*Math.random() will produce smaller integers (around 0) with a higher chance than larger ones (near 1).
Your formula could be something like this:

var position = Math.pow(Math.random(), gameSpeed / 3) * 400 + 200;

Or
Make an array with more lower values than higher ones, for example, to generate random integers between [1,5]. (both inclusive). As an example, your array could be [1,1,1,1,1,2,2,2,3,3,3,4,4,5].

And if you pick an element from that array at random, you'll have a better probability of picking a low number than a high one.

Ignite Your Future with Machine Learning Training!