A-M baby

Task/Monty-Hall-problem/Go/monty-hall-problem.go

@@ -0,0 +1,63 @@
+package main
+
+import (
+    "fmt"
+    "math/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.")
+}