AbsDistinct

A non-empty array A consisting of N numbers is given. The array is sorted in non-decreasing order. The absolute distinct count of this array is the number of distinct absolute values among the elements of the array.

For example, consider array A such that:
  A[0] = -5
  A[1] = -3
  A[2] = -1
  A[3] =  0
  A[4] =  3
  A[5] =  6

The absolute distinct count of this array is 5, because there are 5 distinct absolute values among the elements of this array, namely 0, 1, 3, 5 and 6.

Write a function:

    int solution(vector<int> &A);

that, given a non-empty array A consisting of N numbers, returns absolute distinct count of array A.

For example, given array A such that:
  A[0] = -5
  A[1] = -3
  A[2] = -1
  A[3] =  0
  A[4] =  3
  A[5] =  6

the function should return 5, as explained above.

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 [−2,147,483,648..2,147,483,647];
        array A is sorted in non-decreasing order.

#include <set>

int solution(vector<int> &A) {
    // write your code in C++11 (g++ 4.8.2)
    set<int> s;
    for (auto i: A) {
        s.insert(abs(i));
    }
    
    return s.size();
}