Find the first non-consecutive number Python Codewars

Task:

Your task is to find the first element of an array that is not consecutive.

By not consecutive we mean not exactly 1 larger than the previous element of the array.

E.g. If we have an array [1,2,3,4,6,7,8] then 1 then 2 then 3 then 4 are all consecutive but 6 is not, so that's the first non-consecutive number.

If the whole array is consecutive then return null².

The array will always have at least 2 elements¹ and all elements will be numbers. The numbers will also all be unique and in ascending order. The numbers could be positive or negative and the first non-consecutive could be either too!

Solution:

def first_non_consecutive(arr):
    prev = arr[0]
    first = None
    for num in arr[1:]:
        if (prev + 1) != num:
            first = num
            break
        prev += 1
    return first


print(first_non_consecutive([1,2,3,5,6,7,8]))

Find the first non-consecutive number Solutions | Codewars

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