https://twitter.com/littmath/status/1834273354628424080

coin flip question

import random
import collections


def trial(first_to=2):
    flips = [random.choice([True, False]) for _ in range(100)]
    alice_flip_checks = flips
    bob_flip_checks = [flips[i] for i in range(1, len(flips), 2)] + [flips[i] for i in range(0, len(flips), 2)]
    # get second_head
    try:
        alice_second_head_idx = [i for i, value in enumerate(alice_flip_checks) if value][first_to-1]
    except IndexError:
        alice_second_head_idx = len(flips) + 1
    try:
        bob_second_head_idx = [i for i, value in enumerate(bob_flip_checks) if value][first_to-1]
    except IndexError:
        bob_second_head_idx = len(flips) + 1
    if alice_second_head_idx > bob_second_head_idx:
        return "bob"
    elif alice_second_head_idx == bob_second_head_idx:
        return "tie"
    else:
        return "alice"


def simulate(first_to=2, num_flips=100, num_trials=1000000):
    counts = collections.Counter([trial(50) for _ in range(num_trials)])
    return {k: v / num_trials for k, v in counts.items()}


print("first to 2")
print(simulate(first_to=2))
print("first to 50")
print(simulate(first_to=50))