## The challenge

Write a function:

`def solution(A)`

that, given an array A of N integers, returns the smallest positive integer (greater than 0) that does not occur in A.

For example, given `A = [1, 3, 6, 4, 1, 2]`

, the function should return 5.

Given `A = [1, 2, 3]`

, the function should return 4.

Given `A = [−1, −3]`

, the function should return 1.

Write an **efficient** algorithm for the following assumptions:

- N is an integer within the range [1..100,000];
- each element of array A is an integer within the range [−1,000,000..1,000,000].

## The solution

```
def solution(A):
# sort the list and create a set
# this will remove all duplicates
A = set(sorted(A))
# create the default answer of 1
answer = 1
# loop through all items in set
for i in A:
# if the same as answer
if i == answer:
# increment
answer+=1
# return the answer
return answer
```