MontyHallProblem by Swift

enakai00.hatenablog.com

ここを参考に

というかそのままSwiftで書いてみた。

import Foundation
func game(change:Bool) -> Int {
    
    let correct = Int(arc4random_uniform(3))
    var choice = Int(arc4random_uniform(3))
    
    //モンティが開くドアの決定
    var open = 0
    while true {
        open = Int(arc4random_uniform(3))
        if open != choice && open != correct{ break }
    }
    
    if change {
        for i in 0..<3{
            if i != choice && i != open{
                choice = i
                break
            }
        }
    }
    
    var point = 0
    if choice == correct{ point += 1}
    return point
}

var p = 0
let n = 10000
for _ in 0..<n{
    p += game(true)
}
print(Float(p)/Float(n))

p = 0
for _ in 0..<n{
    p += game(false)
}
print(Float(p)/Float(n))

普通に上手くいく。

output

0.6609
0.333
Program ended with exit code: 0