Fill The Bus

def fillBus(bus_capacity, ppl):
    if bus_capacity <= 0: return [[]][bus_capacity<0:]

    groups = []
    isValid = lambda x: x not in groups and len(x)<=3

    for n in ppl:
        perms = fillBus(bus_capacity-n, ppl)
        perms and [groups.append(c) for m in perms if isValid(c:=[n, *m])]
    return groups

ppl = [3,4,5,7,6,2,4,9,8,2]
print([m for m in fillBus(15, ppl) if len(m)==3])