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Frog Riddle
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#!/usr/bin/env python | |
import random | |
# Frog 0 for female, 1 for male | |
def create_frog(): | |
return random.randint(0, 1) | |
def has_croak(pairs): # also male | |
return 1 in pairs | |
def has_female(frogs): | |
return 0 in frogs | |
def choose_without_croak(choose_two): | |
frogs = [create_frog() for i in range(3)] | |
# first frog at the right side | |
# second and third at the left side | |
if choose_two: | |
return has_female(frogs[1:]) # choose two frogs | |
return has_female(frogs[0:1]) | |
def main(): | |
total = 10000 | |
correct = 0 | |
for i in range(total): | |
correct += choose_without_croak(True) | |
print('Just choose two frogs. Total: {}, correct: {}. P = {}'.format(total, correct, correct / total)) | |
correct = 0 | |
for i in range(total): | |
correct += choose_without_croak(False) | |
print('Just choose one frog. Total: {}, correct: {}. P = {}'.format(total, correct, correct / total)) | |
# The exact question is, | |
# "What is the probability of the frogs in the pair has female, | |
# given that one of them is male?" | |
def exact_calculation(): | |
total = 10000 | |
croak = 0 | |
correct = 0 | |
for i in range(total): | |
frogs = [create_frog() for i in range(3)] | |
if has_croak(frogs[1:]): | |
croak += 1 | |
if has_female(frogs[1:]): | |
correct += 1 | |
print('Total croak: {}, correct: {}. P = {}'.format(croak, correct, correct / croak)) | |
main() | |
exact_calculation() |
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