Challenge

availability_1.py

def availability(start, end, blocks):
    """Return a new list of tuples of ints, where those ints
    represent the time ranges between start and end that
    don't intersect with any blocks.

    Keyword arguments:
    start -- earliest start time we care about
    end -- latest end time we care about
    blocks -- list of tuples of ints that we wish to exclude
    return -- list of tuples of ints
    """
    requested_range = set(range(start, end + 1))
    unavailability = set([i for block in blocks for i in range(block[0]+1, block[1])])
    availability_blocks = sorted(requested_range - unavailability)

    pair = []
    pairs = []
    for i in availability_blocks:
        if pair and i - pair[-1] > 1:
            pairs.append((min(pair), max(pair)))
            pair = []
        pair.append(i)
    pairs.append((min(pair), max(pair)))
    return pairs


print availability(1, 5, [(2,4)]) # [(1, 2), (4, 5)]
print availability(1, 5, []) # [(1, 5)]
print availability(2, 5, [(1,3)]) # [(3, 5)]

print availability(2, 5, [(1,3), (1,3)]) # [(3, 5)] << Redundant unavailability block
print availability(1, 10, [(2,6), (5,9)]) # [(1, 2), (9, 10)] << Overlapping unavailability block