AoC day 23 (LAN Party)

C=[c.split('-') for c in puzzle.splitlines()]                               # parse the pairs of connected gamers
G=defaultdict(lambda:[])                                                    # init dictionary of gamers
for g1,g2 in C: G[g1]+=[g2]; G[g2]+=[g1]                                    # update list of connected partners for each gamer

def part1():                                                                # find the trios of fully interconnected gamers
    trio=set()                                                              # init the set of trios
    for g1,gl in G.items():                                                 # for each gamer's list of connected partners
        for g2,g3 in itertools.combinations(gl,2):                          # keep from all combinations of partner's pairs
            if g2 in G[g3] and (g1[0]=='t' or g2[0]=='t' or g3[0]=='t'):    # the connected pairs making trio of at least one 't' gamer
                trio.add(tuple(sorted([g1,g2,g3])))                         # sort and record this new trio
    print(len(trio))                                                        # display the nbr of unique trios

def part2():                                                                # find the largest LAN of fully interconnected gamers
    LAN=set((g,) for g in G.keys())                                         # start from all groups of 1 gamer
    while(len(LAN)>1):                                                      # keep groups that can grow until there remains only one
        nLAN=set()                                                          # init the new set of groups of incremented size
        for gg in LAN:                                                      # for each gamers group of current LAN
            gg=list(gg)                                                     # tuple>>list transformation only for faster search :)
            for ng in (g for g in G if g not in gg):                        # invite a new gamer from outside the group
                xt=all(ng in G[g] for g in gg)                              # check if he/she is connected with all current members
                if xt: nLAN.add(tuple(sorted(gg+[ng])))                     # if so, extend and record this new larger group
        LAN=nLAN                                                            # replace previous LAN with new LAN of larger groups
    print(','.join(list(LAN)[0]))                                           # display the sorted list of members of largest LAN