Monty Hall/Monty Fall

from struct import unpack

r = open("/dev/urandom","rb")


def randmod3():
    rand = 0xFFFFFFFF
    while rand == 0xFFFFFFFF:
        rand = unpack("I",r.read(4))[0]
    return rand%3

def randmod2():
    rand = unpack("B",r.read(1))[0]
    return rand%2

print "Monty Hall"

switch_win_count = 0
stay_win_count = 0

for i in range(1000000):
    doors = ["goat","goat","goat"]
    doors[randmod3()] = "car"
    choice = randmod3()
    opened = -1
    switch_choice = -1
    possible_doors = {
            0 : [1,2],
            1 : [2,0],
            2 : [0,1]
            }
    remaining_doors = possible_doors.get(choice);
    if doors[choice] != "car":
        if doors[remaining_doors[0]] == "car":
            switch_choice = remaining_doors[0]
            opened = remaining_doors[1]
        else:
            switch_choice = remaining_doors[1]
            opened = remaining_doors[0]
    else:
        rand_door = randmod2()
        opened = remaining_doors[rand_door]
        switch_choice = remaining_doors[(rand_door+1)%2]

    if doors[switch_choice] == "car":
        switch_win_count += 1

    if doors[choice] == "car":
        stay_win_count += 1

print "switch wins: %d" % switch_win_count
print "stay wins: %d" % stay_win_count
print ""
print "Monty Fall"

switch_win_count = 0
stay_win_count = 0

for i in range(1000000):
    doors = ["goat","goat","goat"]
    doors[randmod3()] = "car"
    choice = randmod3()
    opened = -1
    switch_choice = -1
    possible_doors = {
            0 : [1,2],
            1 : [2,0],
            2 : [0,1]
            }
    remaining_doors = possible_doors.get(choice);

    rand_door = randmod2()
    opened = remaining_doors[rand_door]
    switch_choice = remaining_doors[(rand_door+1)%2]

    if doors[switch_choice] == "car":
        switch_win_count += 1

    if doors[choice] == "car":
        stay_win_count += 1

print "switch wins: %d" % switch_win_count
print "stay wins: %d" % stay_win_count