aoc-2020/23.py

input = "137826495"
#input = "389125467"
cups = [int(i) for i in list(input)]
max_cup = max(cups)

def ring_str(after):
    result = ""
    current = 1
    printed = []
    while current not in printed:
        result += str(current)
        printed.append(current)
        current = after[current]
    return result


def run_on_cups(cups, iterations):
    cup_count = len(cups)
    max_cup = max(cups)
    after = {}
    for i in range(0, cup_count - 1):
        after[cups[i]] = cups[i + 1]
    after[cups[-1]] = cups[0]

    current_cup = cups[0]
    for i in range(0, iterations):
        #print("Current:", current_cup)
        #print_ring(after)
        one = after[current_cup]
        two = after[one]
        three = after[two]
        three_cups = [one, two, three]
        #print("Selecting:", three_cups)
        dest = current_cup
        while True:
            dest -= 1
            if dest == 0:
                dest = max_cup
            if dest not in three_cups:
                break
        #print("Destination:", dest)
        after[current_cup] = after[three]
        after[three] = after[dest]
        after[dest] = one
        current_cup = after[current_cup]
    return after

after = run_on_cups(cups, 100)
print("Answer 1:", ring_str(after)[1:])
after = run_on_cups(cups + list(range(10, 1000001)), 10000000)
a = after[1]
b = after[a]
print("Answer 2:", a * b)