sanity check for http://en.wikipedia.org/wiki/Two_envelopes_problem

gistfile1.py

from random import random

envs = [1, 2]

swapping = 0
staying = 0

for x in xrange(100000000):
    if random() <= .5:
        envs.reverse()

    if random() <= .5:
        swapping += envs[1]
    else:
        swapping += envs[0]

for x in xrange(10000000):
    if random() <= .5:
        envs.reverse()

    if random() <= .5:
        staying += envs[0]
    else:
        staying += envs[1]

print 'swapping: ', swapping
print 'staying: ', staying