LeetCode239. 滑动窗口最大值

class Solution {
    static LinkedList<Integer> qres = new LinkedList<Integer>();
    public static int[] maxSlidingWindow(int[] arr,int k) {
        qres.clear();
        if(arr == null || arr.length == 0)
            return new int[] {};
        int index = 0;
        int[] res = new int[arr.length - k + 1];
        for(int i = 0;i < arr.length;i++) {
            while(!qres.isEmpty() && arr[qres.peekLast()] <= arr[i])
                qres.removeLast();
            qres.addLast(i);
            if(qres.peekFirst() == i - k)
                qres.removeFirst();
            if(i >= k - 1)
                res[index++] = arr[qres.peekFirst()];
        }
        return res;
    }
}