Monty Hall problem: Difference between revisions

=={{header|Pascal}}==

<lang pascal>program MontyHall;

uses

sysutils;

const

NumGames = 1000;

{Randomly pick a door(a number between 0 and 2}

function PickDoor(): Integer;

begin

Exit(Trunc(Random * 3));

end;

var

i: Integer;

PrizeDoor: Integer;

ChosenDoor: Integer;

WinsChangingDoors: Integer = 0;

WinsNotChangingDoors: Integer = 0;

begin

Randomize;

for i := 0 to NumGames - 1 do

begin

//randomly picks the prize door

PrizeDoor := PickDoor;

//randomly chooses a door

ChosenDoor := PickDoor;

//if the strategy is not changing doors the only way to win is if the chosen

//door is the one with the prize

if ChosenDoor = PrizeDoor then

Inc(WinsNotChangingDoors);

//if the strategy is changing doors the only way to win is if we choose one

//of the two doors that hasn't the prize, because when we change we change to the prize door.

//The opened door doesn't have a prize

if ChosenDoor <> PrizeDoor then

Inc(WinsChangingDoors);

end;

Writeln('Num of games:' + IntToStr(NumGames));

Writeln('Wins not changing doors:' + IntToStr(WinsNotChangingDoors) + ', ' +

FloatToStr((WinsNotChangingDoors / NumGames) * 100) + '% of total.');

Writeln('Wins changing doors:' + IntToStr(WinsChangingDoors) + ', ' +

FloatToStr((WinsChangingDoors / NumGames) * 100) + '% of total.');

end.

</lang>

Output:

<pre>Num of games:1000

Wins not changing doors:359, 35,9% of total.

Wins changing doors:641, 64,1% of total.</pre>