Algorithm for truck moving around a circle of gas stations

Question

You have a truck moving around a circular track with gas stations spaced out around the circle. Each station has a finite amount of gas. The gas tank on the truck is infinit

Answer 1

static int getIndex(int A[], int B[]) {
    int start = -1;
    int N = A.length;
    for (int i = 0; i < N; i++) {
        int c = A[i] - B[i];
        if (c >= 0) {
            int j = i + 1;
            while (c >= 0 && j < i + N) {
                c += A[j % N] - B[j % N];
                j++;
            }
            if (c >= 0) {
                start = i;
                break;
            }
        }
    }
    return start;
}