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滑动窗口最大值

Sliding Window Maximum

专题
Algorithmic Programming / 算法编程
难度
L4
来源
Citadel

题目详情

问题：滑动窗口最大值

考察：数组、滑动窗口

来源：Citadel

链接：https://www.jointaro.com/interviews/questions/sliding-window-maximum/

You are given an array of integers nums, there is a sliding window of size k which is moving from the very left of the array to the very right. You can only see the k numbers in the window. Each time the sliding window moves right by one position.

Return the max sliding window.

 

Example 1:

Input: nums = [1,3,-1,-3,5,3,6,7], k = 3
Output: [3,3,5,5,6,7]
Explanation: 
Window position                Max
---------------               -----
[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

Example 2:

Input: nums = [1], k = 1
Output: [1]

 

Constraints:

  • 1 <= nums.length <= 105
  • -104 <= nums[i] <= 104
  • 1 <= k <= nums.length
解析

思路：维护一个单调递减双端队列，队列中存下标。新元素进入时弹出所有不大于它的队尾元素，窗口左端越界时弹出队首；队首始终是当前窗口最大值。

复杂度：时间 O(n)，空间 O(k)。