Advent of Code 2020 day 15

sol.py

import math
import collections
import itertools
import re
import ast
import functools

T = "bb.txt"
M = "aa.txt"

file1 = open(M, 'r')
Lines = file1.read().splitlines()

main_input = [0, 1, 4, 13, 15, 12, 16]
test_input = [0, 3, 6]
def part1():
    test = main_input
    max_turn = 30000000
    turn = len(test) + 1
    last_spoken = test[-1]

    ledger = {}
    for i, e in enumerate(test):
        ledger[e] = [i+1]

    while turn <= max_turn:
        if last_spoken in ledger and len(ledger[last_spoken]) == 1:
            last_spoken = 0
        elif last_spoken in ledger and len(ledger[last_spoken]) > 1:
            vals = ledger[last_spoken]
            last_spoken = vals[-1] - vals[-2]
        if last_spoken in ledger:
            ledger[last_spoken].append(turn)
        else:
            ledger[last_spoken] = [turn]
        turn += 1
    return last_spoken

print(part1())