"What is the minimal impact factor of nucleotides contained in a particular part of the given DNA sequence?"

Not sure if my thinking is right, but answer is:

1. If it contains atleast one A then 1.
2. If it contains atleast one B then 2. and so on.

If we have an array of counts of size 'A'-'Z' (26) and another array where we get impacts also in 0(1) time then task can be completed in O(m) were m is length of DNA sqeuence

Hi, looks like your code gives %100 results on the codility test cases. But there is a mistake.

Let's say our input is that :

vector vec = {-2, -1, 0 , 4};

According to your code, function returns 0 because of this line :

if ( A[2] == 0 ) return A[0] * A[1] * A[2];

i think , it should be something like this

if ( A[2] == 0 ) return A[0] * A[1] * A[3];

it gives 8.

Such a test scenario may not have come across on the Codility site.