Homework 2


60 pts., due Mar. 1

In an attempt to discover a new secret code, a programmer thought of the following scheme: ``I could divide a string into halves and interchange them. In fact, I could do this recursively, dividing each half in half and interchanging the pieces. That ought to mix up things pretty well.'' If you think about it for a while, you'll discover another nice feature of this scheme: the same algorithm can be used for coding and decoding.

  1. Write a C++ function which implements this function as described by the programmer. Write a small driver program which allows you to test your function.
  2. Verify that your function can also decode a coded string.
  3. Unfortunately, this algorithm doesn't mix up the characters of a string very well at all. What does the algorithm do? What would be the result of applying this algorithm to the strings "alligator" and "able was i ere i saw elba"?
  4. Write a simpler recursive function (and driver program) that does what this function does.

Turn in copies of your source code and example runs with the input and output.

Thomas P. Kelliher
Mon Feb 19 17:37:09 EST 1996
Tom Kelliher