Read Notes and Credits, the following scene description, and then click on the green flag. The project answers Dr. Dewdney's three questions. Imagine a very large room (see drawing on screen) with a wall with a single opening leading to another room. The room is full of zombies. For unknown reasons, each zombie awakes at a different instant and shuffles in a straight line, perpendicular to the wall. There is a single opening in the wall of width w. If the straight path of any zombie takes it through the opening, then the zombie escapes. If the zombie doesn’t pass through the opening, it strikes the wall and collapses back into a deep sleep.
Zombies Walk is taken from A. K. Dewdney’s Computer Recreations column appearing in the April 1985 issue of Scientific American magazine. The problem is repeated in his book, The Armchair Universe, and is one of the Five Easy Pieces described at the beginning of chapter 6. Dr. Dewdney suggest a Zombies Walk algorithm be written to answer these three questions: 1. If the width of the door is w, what fraction of the mummies that awake from random positions in the room and walk a straight line perpendicular to the wall, can be expected to escape? 2. If an observer stationed just outside the door notes the time between consecutive mummies that escape, how will these inter-arrival times be distributed? 3. What’s the average inter-arrival time? Zombies Walk is about arrival times, and arrival times are statistically important to planners. From bank managers to video game designers, a method for modeling the distribution of arrival times for bank patrons that want service or aliens that need zapping is important. The random number generator in Scratch gives us a simple tool for modeling a distribution used to simulate inter-arrival times.
