CS99 FALL 2002
PRELIM 2
-------------------------------------------------------------------------------
% Problem1

% Inititalize variables:
  clear;
  MAX        = 10;               % 10 marbles to start with
  MIN        = 0;                % can't have neg marables
  whiteTotal = randInt(MIN,MAX); % choose white marbles 
  blackTotal = MAX - whiteTotal; % choose black marbles
  count      = 0;                % taken-marble counts

% Extract marbles until one color runs out
% or both colors run out:
  while whiteTotal >= MIN & blackTotal >= MIN & count < MAX
    
    % Take a marble:
      switch readInt(0,1,'Try to take a marble [0 (W),1 (B)]: ')
       case 0
           if whiteTotal > MIN
	           whiteTotal=whiteTotal-1;
               count = count+1;
           else
               disp('Sorry! Out of white marbles!');
           end
       case 1
           if blackTotal > 0
	           blackTotal=blackTotal-1;
               count = count+1;
           else
               disp('Sorry! Out of black marbles!');
           end
       otherwise
	       error('Error!');
      end
      
  end

% Report total amount of marbles taken. 
  disp(['Total marbles taken: ',num2str(count)]);
-------------------------------------------------------------------------------
% Problem2

% Inititalize variables:
  size = randInt(1,10);
  
% do rows
  fprintf('\n');
  for row=1:size

    % do cols
      for col=1:2*size
      
	if     col <= size-row, fprintf(' ');
	elseif col > size-row & col <= size, fprintf('/');
	elseif col > size & col <= size+row, fprintf('\\');
	else   fprintf(' ');
	end
	
      end
      
      fprintf('\n');
      
  end

  for row=size+1:2*size

    % do cols
      for col=1:2*size
      
	if     col < row-size, fprintf(' ');
	elseif col >= row-size & col <= size, fprintf('\\');
	elseif col > size &  col <= 3*size-row+1 , fprintf('/');
	else   fprintf(' ');
	end
	
      end
      
      fprintf('\n');
      
  end

  fprintf('\n');
  
  
% Example session:

%    /\
%   //\\
%  ///\\\
%  \\\///
%   \\//
%    \/


-------------------------------------------------------------------------------
% Problem 3

function test = Problem3()
% PROBLEM3 Test randChars

  test = randChars(2,4);
  
function result = randChars(rows,cols) 
% RANDCHARS fill array with random lowercase letters

% Fill array $a$ with random lowercase letters:
  for r=1:rows
    for c=1:cols
      result(r,c)=char(randInt(double('a'),double('z')));
    end
  end

  % more compressed answer:
  % result=char(floor(rand(rows,cols)*('z'-'a'+1))+floor('a'))
-------------------------------------------------------------------------------
% Problem 4

function result = Problem4()
  result = core(rand(4,5));
  
function result = core(x)
  result = x(2:end-1,2:end-1);