Monty Hall problem: Difference between revisions

=={{header|Go}}==

<lang go>package main

import (

"fmt"

"rand"

)

func main() {

games := 1000000

var switchWinsCar, keepWinsCar int

for i := 0; i < games; i++ {

// simulate game

carDoor := rand.Intn(3)

firstChoice := rand.Intn(3)

var hostOpens int

if carDoor == firstChoice {

hostOpens = rand.Intn(2)

if hostOpens >= carDoor {

hostOpens++

}

} else {

hostOpens = 3 - carDoor - firstChoice

}

remainingDoor := 3 - hostOpens - firstChoice

// some assertions that above code produced a valid game state

if carDoor < 0 || carDoor > 2 {

panic("car behind invalid door")

}

if firstChoice < 0 || firstChoice > 2 {

panic("contestant chose invalid door")

}

if hostOpens < 0 || hostOpens > 2 {

panic("host opened invalid door")

}

if hostOpens == carDoor {

panic("host opened door with car")

}

if hostOpens == firstChoice {

panic("host opened contestant's first choice")

}

if remainingDoor < 0 || remainingDoor > 2 {

panic("remaining door invalid")

}

if remainingDoor == firstChoice {

panic("remaining door same as contestant's first choice")

}

if remainingDoor == hostOpens {

panic("remaining door same as one host opened")

}

// tally results

if firstChoice == carDoor {

keepWinsCar++

}

if remainingDoor == carDoor {

switchWinsCar++

}

}

fmt.Println("In", games, "games,")

fmt.Println("switching doors won the car", switchWinsCar, "times,")

fmt.Println("keeping same door won the car", keepWinsCar, "times.")

}</lang>

Output:

<pre>

In 1000000 games,

switching doors won the car 666358 times,

keeping same door won the car 333642 times.

</pre>