% CS99 Fall 2001
% Prelim 2 Solutions
%-----------------------------------------------------------------------------%
% Problem 1

depth = str2double(input('Enter the depth: ','s'));		    
while ~isreal(depth) | isinf(depth) | isnan(depth) | ~isnumeric(depth) | ...
     floor(depth)~=ceil(depth) | depth < 1
  disp(['Please enter a legal integer!']);                                   
  depth = str2double(input('Enter the depth: ','s'));		
end                                                                         

% Approach 1:
for row=1:depth

  % print whitespace:
  for col=1:depth-row
    fprintf(' ');
  end
  % print stars:
  for col=1:row*2+1
    fprintf('*');
  end

  % advance to the next line:
  fprintf('\n');  
  
end

% Approach 2:
for row=1:depth

  for col=1:depth+row+1
    if col<=depth-row
      fprintf(' ');
    else
      fprintf('*');
    end
  end
  
  % advance to the next line:
  fprintf('\n');  
  
end
%-----------------------------------------------------------------------------%
% Problem 2

values = [1 2 3; 4 5 6; 7 8 9];

% approach 1:
[rows cols] = size(values);
sums = zeros(1,rows);
for col=1:cols
  for row=1:rows
    sums(col) = sums(col)+values(row,col);
  end
end
sums

% approach 2:
sums = sum(values);
%-----------------------------------------------------------------------------%
% Problem 3                                                                   %
%-----------------------------------------------------------------------------%
% Algorithm:
% =========
% + Start from a non-moving position  
%   - no calories burned so far
%   - no cycles performed so far
% + Determine if people stop prematurely
% + If people haven't decided to stop and the cycles have not finished
%   - contribute calories from each person
%   - increment the amount of cycles so far
%   - determine if the people want to stop prematurely
%   - repeat
% + If the people stopped before playing (no cycles),
%   - report no cycles and calories burned
% + Otherwise,
%   - report cycles and calories burned
%-----------------------------------------------------------------------------%

% Initialize variables:
  MAXCYCLES = 25;   % max number of cycles to "play"
  BOREDOM = 10;     % percent of time
  cycles = 0;       % cycles "played" so far
  CALORIE = 10;     % amount of calories per person per cycle
  calories = 0;     % amount of calories consumed so far
  continueFlag = 1; % flag to signal whether or not to continue
  
% Initial check if people stop early:
  stopValue = floor(rand*10) + 1; % random number between 1 and 10
  if stopValue == 1;
    continueFlag = 0;
  end
  
% Add calories for each cycle if the people do not stop prematurely
% the cycles are not exhausted:
  while continueFlag & cycles < MAXCYCLES
    
    % Contribute calories from each person:
      calories = calories+2*CALORIE;
  
    % Increment cycles:
      cycles = cycles + 1;
      
    % Check for a premature stop:
      stopValue = floor(rand*10) + 1; % random number between 1 and 10
      if stopValue == 1;
	continueFlag = 0;
      end

    % Repeat:   
  end
  
% Report results:
  if cycles==0
    disp(['The people did not play.']);
  elseif cycles < MAXCYCLES
    disp(['The people stopped prematurely.']);
  else
    disp(['The people played an entire game.']);
  end
  disp(['Amount of calories burned: ',num2str(calories)]);
%-----------------------------------------------------------------------------%