class Solution {
    public int shortestSubarray(int[] A, int K) {
        int N = A.length;
        int res = N + 1;

        long[] B = new long[N + 1];
        for (int i = 0; i < N; i++) {
            B[i + 1] = B[i] + A[i];
        }

        Deque<Integer> d = new ArrayDeque<>();
        for (int i = 0; i < N + 1; i++) {
            while (d.size() > 0 && B[i] - B[d.getFirst()]  >=  K) {
                res = Math.min(res, i - d.pollFirst());
            }
            while (d.size() > 0 && B[i] <= B[d.getLast()]) {
                d.pollLast();
            }
            d.addLast(i);
        }
        return res <= N ? res : -1;
    }
}