Digital Plumber

In [45]:

    

import csv
from collections import defaultdict

def parse(input_path):
    pipes = defaultdict(set)
    with open(input_path, 'rt') as f_input:
        csv_reader = csv.reader(f_input, delimiter=' ')
        for l in csv_reader:
            pipes[int(l[0])] = set([int(n.rstrip(',')) for n in l[2:]])
    for k in pipes:
        for n in pipes[k]:
            pipes[n].add(k)
    return pipes

def connected(node, pipes):
    neighbors = pipes[node]
    pending = list(neighbors)
    while pending:
        alice = pending.pop(0)
        for bob in pipes[alice]:
            if bob in neighbors:
                pass
            else:
                neighbors.add(bob)
                pending.append(bob)
    return neighbors

def length_neighborhood(input_path, node):
    pipes = parse(input_path)
    return len(connected(node, pipes))


    

In [53]:

    

assert(length_neighborhood('input.test1.txt', 0) == 6)


    

In [47]:

    

length_neighborhood('input.txt', 0)


    

    
Out[47]:





141

In [51]:

    

def no_groups(input_path):
    pipes = parse(input_path)
    covered = set()
    group_count = 0
    for node in pipes:
        if node not in covered:
            neighbors = connected(node, pipes)
            covered = covered.union(neighbors)
            group_count += 1
    return group_count


    

In [54]:

    

assert(no_groups('input.test1.txt') == 2)


    

In [55]:

    

no_groups('input.txt')


    

    
Out[55]:





171