In this challenge, we will calculate the minimum number that is not a possible sum from a list of positive integers.

Examples

solve([1,2,8,7]) = 4
we can get 1, 2, 3 (from 1+2), but we cannot get 4. 4 is the smallest number not retrievable from the list.

solve([4,1,2,3,12]) = 11
We can get 1, 2, 3, 4, 4+1=5, 4+2=6, 4+3=7, 4+3+1=8, 4+3+2=9, 4+3+2+1=10. But we can't get to 11.

solve([2,3,2,3,4,2,12,3]) = 1. We cannot get 1.

Tests

solve([4,2,8,3,1])
solve([4,2,7,3,1])
solve([1,2,8,7])
solve([4,2,12,3])

Good luck!

This challenge comes from KenKamau on CodeWars. Thank you to CodeWars, who has licensed redistribution of this challenge under the 2-Clause BSD License!

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