面试题 59 - I. 滑动窗口的最大值

输入: nums = [1,3,-1,-3,5,3,6,7], 和 k = 3
输出: [3,3,5,5,6,7]
解释:

  滑动窗口的位置                最大值
---------------               -----
[1  3  -1] -3  5  3  6  7       3
 1 [3  -1  -3] 5  3  6  7       3
 1  3 [-1  -3  5] 3  6  7       5
 1  3  -1 [-3  5  3] 6  7       5
 1  3  -1  -3 [5  3  6] 7       6
 1  3  -1  -3  5 [3  6  7]      7

class Solution:
    def maxSlidingWindow(self, nums: List[int], k: int) -> List[int]:
        q, res = [], []
        for i, num in enumerate(nums):
            while len(q) != 0 and nums[q[-1]] <= num:
                q.pop(-1)
            q.append(i)

            if q[0] == i - k:
                q = q[1:]
            if i >= k - 1:
                res.append(nums[q[0]])
        return res

class Solution {
    public int[] maxSlidingWindow(int[] nums, int k) {
        int index = 0, n = nums.length;
        if (k == 0 || n == 0) {
            return new int[0];
        }
        int[] res = new int[n - k + 1];
        LinkedList<Integer> q = new LinkedList<>();
        for (int i = 0; i < n; ++i) {
            while (!q.isEmpty() && nums[q.peekLast()] <= nums[i]) {
                q.pollLast();
            }
            q.addLast(i);
            if (q.peekFirst() == i - k) {
                q.pollFirst();
            }
            if (i >= k - 1) {
                res[index++] = nums[q.peekFirst()];
            }
        }
        return res;
    }
}

/**
 * @param {number[]} nums
 * @param {number} k
 * @return {number[]}
 */
var maxSlidingWindow = function (nums, k) {
  if (!nums.length || !k) return [];
  if (k === 1) return nums;
  let res = [];
  let tmpMax = -Infinity;
  let len = nums.length;
  let window = [];
  for (let i = 0; i < k; i++) {
    tmpMax = Math.max(nums[i], tmpMax);
    window.push(nums[i]);
  }
  res.push(tmpMax);
  for (let i = k; i < len; i++) {
    let a = window.shift();
    window.push(nums[i]);
    if (nums[i] > tmpMax) {
      tmpMax = nums[i];
    } else if (tmpMax === a) {
      tmpMax = Math.max(...window);
    }
    res.push(tmpMax);
  }
  return res;
};