Try to find a meeting time that works for our team

gistfile1.txt

tzs = [
    ("GMT", 0),
    ("Boston", -4),
    ("Denver", -6),
    ("Singapore", +8),
    ("Kyiv", +3),
]

def time_in(city, offset):
    return city, [(offset + i + 24) % 24 for i in range(24)]

good_times = {}
for city, offset in tzs:
    city, times = time_in(city, offset)
    offsets = [i for i, t in enumerate(times) if 6 <= t <= 20]
    good_times[city] = offsets
    print("{0:12} {1}".format(city, " ".join("{0:02d}".format(t) for t in times)))

print(sorted(reduce(
    lambda a, b: set(a).intersection(set(b)),
    good_times.values(),
    set(range(24))
)))

from collections import Counter

c = Counter(
    i
    for good_time in good_times.values()
    for i in good_time
)
print(c)