Monty Hall problem: Difference between revisions
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Type: SExpression
</pre>
=={{header|SparForte}}==
As a structured script.
<syntaxhighlight lang="ada">#!/usr/local/bin/spar
pragma annotate( summary, "monty" )
@( description, "Run random simulations of the Monty Hall game. Show the" )
@( description, "effects of a strategy of the contestant always keeping" )
@( description, "his first guess so it can be contrasted with the" )
@( description, "strategy of the contestant always switching his guess." )
@( description, "Simulate at least a thousand games using three doors" )
@( description, "for each strategy and show the results in such a way as" )
@( description, "to make it easy to compare the effects of each strategy." )
@( see_also, "http://rosettacode.org/wiki/Monty_Hall_problem" )
@( author, "Ken O. Burtch" );
pragma license( unrestricted );
pragma restriction( no_external_commands );
procedure monty is
num_iterations : constant positive := 100_000;
type action_type is (stay, switch);
type prize_type is (goat, pig, car);
doors : array(1..3) of prize_type;
type door_index is new positive;
-- place the prizes behind random doors
procedure set_prizes is
begin
doors( 1 ) := goat;
doors( 2 ) := pig;
doors( 3 ) := car;
arrays.shuffle( doors );
end set_prizes;
-- determine if the prize was chosen based on strategy
function play( action : action_type ) return prize_type is
chosen : door_index := door_index( numerics.rnd(3) );
monty : door_index;
begin
set_prizes;
for i in arrays.first(doors)..arrays.last(doors) loop
if i /= chosen and doors(i) /= car then
monty := i;
end if;
end loop;
if action = switch then
for i in arrays.first(doors)..arrays.last(doors) loop
if i /= monty and i /= chosen then
chosen := i;
exit;
end if;
end loop;
end if;
return doors( chosen );
end play;
winners : natural; -- times won
pct : float; -- percentage won
begin
winners := 0;
for i in 1..num_iterations loop
if play( stay ) = car then
winners := @+1;
end if;
end loop;
pct := float( winners * 100 ) / float( num_iterations );
put( "Stay: count" ) @ ( winners ) @ ( " = " ) @ ( pct ) @ ( "%" );
new_line;
winners := 0;
for i in 1..num_iterations loop
if play( switch ) = car then
winners := @+1;
end if;
end loop;
pct := float( winners * 100 ) / float( num_iterations );
put( "Switch: count" ) @ ( winners ) @ ( " = " ) @ ( pct ) @ ( "%" );
new_line;
end monty;</syntaxhighlight>
=={{header|Stata}}==
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