function ThreeDoors(n,it)
%function ThreeDoors(n,it)
%
% n = number of doors
% it = number of iterations
% the showmaster will always open n-2 doors that do not contain the price.


if nargin < 2
    it = 1000;
end
if nargin < 1
    n = 3;
end

not_switch_count = 0;
switch_count = 0;

not_switch_average = zeros(1,it);
switch_average = zeros(1,it);

for i=1:it
    
    r1 = randperm(n);
    gift_door = r1(1);
    
    r2 = randperm(n);
    chosen_door = r2(1);
    
    if chosen_door == gift_door
        not_switch_count = not_switch_count + 1;
    else
        switch_count = switch_count + 1;
    end
    
    not_switch_average(i) = not_switch_count / i;
    switch_average(i) = switch_count / i;

    figure(1);clf;
    colordef black
    set(gcf,'doublebuffer','on');
    plot(1:i,not_switch_average(1:i),'r-','linewidth',2);hold on;
    plot(1:i,switch_average(1:i),'g-','linewidth',2);
    drawnow;
    
end