Product features · Earliest-finish interval selection

def interval_selection(intervals):
    if type(intervals) is not list or len(intervals) > 64:
        raise ValueError("schedule.input")
    ordered = []
    for index, pair in enumerate(intervals):
        if type(pair) not in (list, tuple) or len(pair) != 2 or any(type(x) is not int or abs(x) > 10**9 for x in pair):
            raise ValueError("schedule.pair")
        start, end = pair
        if start >= end:
            raise ValueError("schedule.interval")
        ordered.append((end, start, index))
    selected, last = [], None
    for end, start, index in sorted(ordered):
        if last is None or start >= last:
            selected.append(index)
            last = end
    return selected