import time
start_time = time.time()

with open('puzzle.txt', 'r') as f:
    line = f.read()

disk_string = []

file = True

file_id = 0

for char in list(line):
    if file:
        disk_string += [str(file_id)] * int(char)
        file_id += 1

    else:
        disk_string += ['.'] * int(char)

    file = not file

for index_a, char_a in enumerate(disk_string[::-1]):
    if char_a != '.':
        for index_b, char_b in enumerate(disk_string):
            if char_b == '.':
                disk_string[index_b] = char_a
                disk_string.pop(-1)
                while disk_string[-1] == '.':
                    disk_string.pop(-1)
                break

checksum = 0

for index, char in enumerate(disk_string):
    checksum += int(char) * index

print(checksum)
print(f'Total time: {time.time() - start_time}')