# 12:58 PM 12/1/2011
# based on playing Portal2, trying to figure out the typical
# number of tries to win 3 rock-paper-scissors in a row by
# a Monte Carlo simulation.

import random

MAX_SIMULATION_RUNS = 1000
WINS_REQUIRED = 3

def	Random(N):
	return random.randrange(N)

handtype = ( 'R', 'P', 'S',)
resulttype = ( '>', '=', '<',)

# 0 - A wins, 1 - tie, 2 - B wins
def	calcresult(a,b):
	return ((b - a) + 4) % 3

def	buildresultstring(a,b):
	s = "%c" % handtype[a]
	s = s + "%c" % resulttype[calcresult(a,b)]
	s = s + "%c" % handtype[b]
	return s

totalplaycount = 0

gamelenhistory = []

for simulation_run in range(MAX_SIMULATION_RUNS):
	print "Simulation number %u:" % simulation_run
	winner = 0
	playcount = 0
	while winner < WINS_REQUIRED:
		playcount +=1
		a = Random(3)
		b = Random(3)
		print buildresultstring(a,b),
		if calcresult(a,b) == 0:
			winner += 1
		else:
			winner = 0
	print "WIN in %u!" % playcount
	totalplaycount += playcount
	gamelenhistory.append(playcount)

print "Average of %0.1f tries to win %u in a row." % (
			float(totalplaycount) / MAX_SIMULATION_RUNS,
			WINS_REQUIRED)

gamelenhistory = sorted( gamelenhistory)

print "Median is about %u tries." % ( gamelenhistory[
			len(gamelenhistory) >> 1])