Problem 1, Mathematical Expresssions

The solution for this problem is in the calculate() method of the Node
class. The class also has methods for creating the expression tree.

There is not a command-line interface, but you can examine the tests
to see how the calculate() method can be exercised.

To run the tests:

    $ python problem1_math_expr.py


-----

Problem 2, Coins

The core algorithms for this solution are in the functions change() and
how_much_change_do_i_use().

change() uses brute force to find all of the ways the specified coins
can be used to represent the price.

how_much_change_do_i_use() filters the results of change() down to the 
solutions with the smallest numbers of coins.

There is a command-line interface. To see the help, and an example:

    $ python problem2_coins.py -h

To run the tests:

    $ python problem2_coins.py -t


-----

Problem3, Substrings

This solution does not have a command-line interface.

The docstring in the module has notes about the implementation.

To run the tests:

    $ python problem3_substrings.py



-----

Problem4, Number Spirals

There is a command-line interface for this program. To see the help:

    $ python problem4_number_sprials.py -h


To run the tests:

    $ python problem4_number_spirals.py -t




Mark Kohler
[email protected]