Simple simulation of Spiegel Riddle (http://www.spiegel.de/wissenschaft/mensch/die-cleveren-gangster-raetsel-der-woche-a-1230429.html)

spiegelriddle.py

import random

# Set the following arguments
noSimulations = 100000

# The following graph is saved in the dictionary "graph"
#
# A--B--C--D
# |  |  |  |
# E--F--G--H
# |  |  |  |
# I--J--K--L
#
# A player moves from A to L by randomly choosing a path, moving only from top to bottom or left to right.

graph = {"a": ("b", "e"), "b": ("c", "f"), "c": ("d", "g"), "d": ("h"), "e": (
    "f", "i"), "f": ("j", "g"), "g": ("h", "k"), "h": ("l"), "i": ("j"), "j": ("k"), "k": ("l")}


def moveThroughGraph():
    startNode = "a"
    currentNode = startNode
    nodesVisited = []
    nodesVisited.append(startNode)
    for i in range(0, 5):
        currentNode = random.choice(graph[currentNode])
        nodesVisited.append(currentNode)
    return nodesVisited


def getSimulations():
    allSimulations = []
    for i in range(noSimulations):
        allSimulations.append(moveThroughGraph())
    return allSimulations


def evaluateSimulations(simulationList):
    count = 0
    for simulation in simulationList:
        if observerAt in simulation:
            count += 1
    return count


if __name__ == "__main__":
    for observerAt in ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l"]:
        observerAtSpecifiedPointCount = evaluateSimulations(getSimulations())
        print("The observer has been seen %d out of %d times at point %s. He was observerd with a probability of %s"
              % (observerAtSpecifiedPointCount, noSimulations, observerAt, "{0:.0%}".format(float(observerAtSpecifiedPointCount)/float(noSimulations))))