missing.py

"""Given a list of numbers 1...max_num, find which one is missing in a list."""


def missing_number(nums, max_num):
    """Given a list of numbers 1...max_num, find which one is missing.

    *nums*: list of numbers 1..[max_num]; exactly one digit will be missing.
    *max_num*: Largest potential number in list

    >>> missing_number([7, 3, 2, 4, 5, 6, 1, 9, 10], 10)
    8

    """

    counter = 1
    nums = sorted(nums)
    for num in nums:
        if num != counter:
            return num - 1
        counter += 1
    if counter == max_num:
        return max_num
    else:
        raise Exception("None are missing!")


if __name__ == '__main__':
    import doctest
    if doctest.testmod().failed == 0:
        print "\n*** ALL TESTS PASS. NICELY DONE!\n"