Virtual HW #6: CODING DECISION TREES IN PASCAL

Corrected Version

                              D--------------
                               | I play OO; |
                               |   I win!   |
                               --------------
                              /
                           X /
                            /
             B-------------/
              | I play O; |
              | your move |
              -------------\
             /              \
          X /             XX \
           /                  E-------------
A---------/                    | I play O; | <--NOTE CORRECTION
 | Your  |                     |   I win!  |
 | move! |                     -------------
 ---------\
           \                  F-------------
         XX \                 /|  You win! |
             \             X / -------------
             C--------------/
              | I play OO; |
              | your move  |
              --------------\
                             \
                           XX \
                              G------------
                               | That's   |
                               | illegal! |
                               ------------

Hint: Here's the top-level design (= the code for decision tree "A") to get you started (recall from the online lecture notes that "<>" is Pascal's way of saying "is not equal to"):

program Nim5; {Question to think about:}
              {why can't I call this   }
              {"5-Nim" ?               }

var yourmove : varying [20] of char;

begin {Nim5}
  
  writeln('Your move!');
  readln(yourmove);
  if yourmove = 'X'
     then begin {if yourmove = 'X'}
            {put code for decision tree "B" here}
          end   {if yourmove = 'X'}
     else begin {if yourmove <> 'X'}
            {put code for decision tree "C" here}
          end   {if yourmove <> 'X'}

end.  {Nim5}

Further hint: The code for decision trees "B" and "C" will look almost exactly like the code for decision tree "A": It will be a sequence (or "compound statement") consisting of a "writeln" instruction, followed by a "readln" instruction, followed by an "if-then-else" instruction.