LISP Programs HiLow is a childrens game in which the player attempts to guess a number given an initial upper and lower bound. As a programming exercise, HiLow provides an introduction to recursive programming with multiple procedures. At a more advanced level, it teaches children about binary search.
Binary search involves dividing the search space in half, and then testing one of the two halves.
The result of the test will then allow the player to throw out one of the halves. Successive application of this technique will allow the player to guess the number correctly using the fewest number of guesses. HiLow was implemented in LISP, and is available for free downloading from this site. The following is a sample game of HiLow. Actual user-inputs are displayed in BOLD type.