#!/bin/python

import time

# Source node: [Destination nodes]
edges = {}

# Returns amount of paths
def find_all_paths(start, target):
    #print(f"Checking from {start} to {target}")
    if start == target:
        return 1

    total = 0
    for node in edges[start]:
        if node > target:
            continue

        total += find_all_paths(node, target)
    
    return total

with open("input", 'r') as input:
    adapters = [int(i.strip()) for i in input]

    adapters.sort()
    adapters.insert(0, 0)
    adapters.append(adapters[-1]+3)
    i = 0
    while i < len(adapters)-1:
        source = adapters[i]
        edges[source] = []
        j = i+1
        while j < len(adapters)-1 and adapters[j]-source <= 3:
            edges[source].append(adapters[j])
            j += 1
        i += 1
    

    print(edges)

    start_time = time.time()

    print(find_all_paths(adapters[0], adapters[-1]))

    print(f"Calculation time: {time.time() - start_time}")