[Lesson 5] Prefix Sums - PassingCars

https://app.codility.com/programmers/lessons/5-prefix_sums/passing_cars/

PassingCars coding task - Learn to Code - Codility

class Solution {
    public int solution(int[] A) {
        int sum = 0;
        int result = 0;

        for (int i = A.length - 1; i >= 0; i--) {
            if (A[i] == 1) {
                sum += 1;
            } else {
                result += sum;
            }

            if (result > 1000000000) {
                return -1;
            }
        }

        return result;
    }
}