aoc_day10_2020.py

adapters = [int(x) for x in INPUT.split("\n")]

# Part 1
last = 0
differences = []
for n in sorted(adapters):
    differences.append(n - last)
    last = n
differences.append(3)

print(differences.count(1) * differences.count(3))

# Part 2

G = nx.DiGraph()
G.add_node(max(adapters) + 3)

for n in [0] + adapters:
    G.add_node(n)
    for x in range(1, 4):
        if n + x in adapters or n + x == max(adapters) + 3:
            G.add_edge(n, n + x)

splits = []
for i, n in enumerate(sorted([0] + adapters)):
    # A split is where there's only one path through
    if n == 0:
        splits.append(0)
    if n - 2 not in adapters and n - 1 not in adapters and i > 2:
        # have to go through this one
        splits.append(n)
splits.append((max(adapters) + 3))

total = 1
start = 0
for end in splits[1:]:
    foo = list(nx.all_simple_paths(G, start, end))
    total *= len(foo)
    start = end

print(total)