Assignment 11

Problems

  1. In the notes we developed a working "Pitcher Problem" solver pitcher_new_2_succint.py. There is a hitch though. Its output does not in fact tell us how to solve the problem, only that it can be solved. Modify the code developed in the notes so that it outputs instructions on how to solve the problem (if it can be), e.g.

     
Fill the 7 litre pitcher.
Pour from the 7 litre pitcher into the 3 litre pitcher.
Empty the 3 litre pitcher.
Pour from the 7 litre pitcher into the 3 litre pitcher.
There will be 1 litre in the 7 litre pitcher.

    Hint: The easiest way that has occurred to me of doing this is to modify the state variable so that it includes a list of instructions on how the state was reached, i.e. start = [ [Pitcher(7,0),Pitcher(3,0], [] ] And that empty list following the list of Pitchers will contain a list of string instructions on how to reach the state. After each fill, pour or empty action add a new string to that list saying what you just did so that when you discover a state is a solution you'll it will contain the list of instructions on how it was reached.

  2. Write a function called summarize that is passed the name of a file whose lines contain data formatted like this,

    continent:country:population:area

    and returns a string containing a report formatting the data exactly like this,

    CONTINENT       COUNTRY    POPULATION       AREA       POP. DEN.
                          (,000,000s)   (,000s MI^2)  (POP./MI^2)

Asia            China         1032          3705         278.5
                India          746          1267         588.8
                Japan          120           144         833.3
                USSR           275          8649          31.8
                              ----         -----
                Total         2173         13765

Europe          England         56            94         595.7
                France          55           211         260.7
                Germany         61            96         635.4
                              ----         -----
                Total          172           401

North America   Canada          25          3852           6.5
                Mexico          78           762         102.4
                USA            237          3615          65.6
                              ----         -----
                Total          340          8229

South America   Brasil         134          3286          40.8
                              ----         -----
                Total          134          3286

    Now it's hard to compare your output with the model output above (that requires detailed data processing after all!) so the file a11p2_tester.py contains a program to test your function for you.

    Tip:

Logistics