Hardcore tech-interview style riddles and mathematical puzzles

ChatGPT got the snail one wrong over and over, not parsing that on the 16th day there will be no night for the snail to fall back down 4 meters:

Let's analyze the snail's progress:

During the day, the snail climbs 5 meters upwards. During the night, it slides 4 meters downwards.

So, in a day, the snail effectively moves 5 - 4 = 1 meter upwards.

To calculate the number of days required for the snail to reach the top of the well, we need to determine how many 1-meter increments are necessary to cover the remaining distance of 20 meters.

20 meters / 1 meter = 20 days

Therefore, it will take the snail 20 days to reach the top of the well.