How to see if the list contains consecutive numbers

Question

I want to test if a list contains consecutive integers and no repetition of numbers. For example, if I have

l = [1, 3, 5, 2, 4, 6]

It should re

Answer 1

Once you verify that the list has no duplicates, just compute the sum of the integers between min(l) and max(l):

def check(l):
    total = 0
    minimum = float('+inf')
    maximum = float('-inf')

    seen = set()

    for n in l:
        if n in seen:
            return False

        seen.add(n)

        if n < minimum:
            minimum = n

        if n > maximum:
            maximum = n

        total += n

    if 2 * total != maximum * (maximum + 1) - minimum * (minimum - 1):
        return False

    return True