50/50 simulation of WWTBAM

gistfile1.txt

% python3 millionaire.py
Out of 1000000 cases
Initial was eliminated in 499869 cases (49.9869 %)
Initial was not eliminated in 500131 cases (50.0131 %)
There answer was different from initial in 249818 cases
Thus changing is winning 49.95051296560301 % if initial was not eliminated

millionaire5050.py

#!/usr/bin/python3

import random

N = 1000000
initial_eliminated = 0
initial_not_eliminated = 0
wins_for_change = 0

for i in range(N):
    # 1 answer among 'ABCD' is correct
    answer = random.choice('ABCD')
    
    # initial answer is also chosen at random
    initial = random.choice('ABCD')
    
    # the wrong answers are thus the set of all answers
    # less the correct answer.
    wrong = set('ABCD') - set(answer)
    
    # we choose 1 of these wrong answers at random
    # to remain alongside with the right answer
    wrong_after_elimination = random.choice(list(wrong))
    
    # if initial is among correct answer and "wrong-after elimination"
    if initial in [answer, wrong_after_elimination]:
        initial_not_eliminated += 1
        
        # if initial is *not* the answer, then increase wins for change
        if initial != answer:
            wins_for_change += 1

    # eles initial answer was just eliminated.
    else:
        initial_eliminated += 1

print('Out of {} cases'.format(N))
print('Initial was eliminated in {} cases ({} %)'
    .format(initial_eliminated, 100 * initial_eliminated / N))
print('Initial was not eliminated in {} cases ({} %)'
    .format(initial_not_eliminated, 100 * initial_not_eliminated / N))
print('There answer was different from initial in {} cases'
    .format(wins_for_change))
print('Thus changing is winning {} % if initial was not eliminated'
    .format(100 * wins_for_change / initial_not_eliminated))