In the case of the JS solution, it runs horribly and is highly inefficient.[0]
For non-hot code, it is perfectly fine, but in this case, inside of a main loop like this it is a waste of cpu cyles. Compare the amount of forests here:
$ node orig-magicForest.js 117 155 106
total forests: 1522899
{ goats: 0, wolves: 0, lions: 223 }
total time: 816ms
$ node new-magicForest.js 117 155 106
total forests: 428
{ goats: 0, wolves: 0, lions: 223 }
total time: 6ms
For non-hot code, it is perfectly fine, but in this case, inside of a main loop like this it is a waste of cpu cyles. Compare the amount of forests here:
[0] https://gist.github.com/chapel/1c038b2bf64b3037aaea