I've played this game a few times, but it's been awhile. I can't quite remember where the snake puzzle is encountered. Try this link to some youtube gameplay videos. This is Part 1, but they go all the way through the game. You will probably have better luck finding which of the parts includes the snake puzzle. I don't remember having any problems with it, but like I said, it's been a long time since I played it. The videos are for XBox, but the gameplay should be the same, just different buttons to push instead of keys.
https://www.youtube.com/watch?v=zkwmgCyg3vk