public int[] maxSlidingWindow(int[] nums, int k) {

        if (nums == null || k <= 0) return new int[0];

        int n = nums.length;

        int[] r = new int[n - k + 1];

        int ri = 0;

        Deque<Integer> q = new ArrayDeque<>();

        for (int i = 0; i < nums.length; i++)

        {

            while (!q.isEmpty() && q.peek() < i - k + 1){

                q.poll();

            }

            while (!q.isEmpty() && nums[q.peekLast()] < nums[i])

            {

                q.pollLast();

            }

            q.offer(i);

            if (i >= k - 1)

            {

                r[ri++] = nums[q.peek()];

            }

        }

        return r;

    }

    public int canCompleteCircuit(int[] gas, int[] cost) {

         if(gas==null || gas.length==0 || cost==null || cost.length==0 || gas.length!=cost.length)

             return -1;

        int total = 0, sum = 0, point = -1;

        for (int i = 0; i < gas.length; i++)

        {

            int diff = gas[i] - cost[i];

            total += diff; sum += diff;

            if (sum < 0){

                sum = 0; point = i;

            }

        }

        return total >= 0 ? point + 1: -1;

    }

    public int candy(int[] ratings) {

        int[] candys = new int[ratings.length];

        Arrays.fill(candys, 1);

        for (int i = 1; i < ratings.length; i++)

        {

            if (ratings[i] > ratings[i-1])

                candys[i] = candys[i - 1] + 1;

        }

        for (int i = ratings.length - 2; i >= 0; i--)

        {

            if (ratings[i] > ratings[i+1])

                candys[i] = Math.max(candys[i], candys[i + 1] + 1);

        }

        int res = 0;

        for(int i : candys)

        {

            res += i;

        }

        return res;

    }