LeetCode题解(0239)：滑动窗口最大值(Python)

题目：​​原题链接​​（困难）

标签：数组、队列、滑动窗口

解法一：

class Solution:
    def maxSlidingWindow(self, nums: List[int], k: int) -> List[int]:
        if not nums:
            return []

        ans = [max(nums[:k])]
        for i in range(k, len(nums)):
            if nums[i] >= ans[-1]:
                ans.append(nums[i])
            elif nums[i - k] == ans[-1]:
                ans.append(max(nums[i - k + 1:i + 1]))
            else:
                ans.append(ans[-1])

        return ans

解法二（双向队列）：

class Solution:

def maxSlidingWindow(self, nums: List[int], k: int) -> List[int]:

# 处理特殊情况

​ if not nums or k == 0:

​ return []

​ if k == 1:

​ return nums

# 初始化滑动窗口队列
    queue = collections.deque()

    max_idx = 0

    for i in range(k):
        if queue and queue[0] == i - k:
            queue.popleft()

        while queue and nums[queue[-1]] < nums[i]:
            queue.pop()

        queue.append(i)

        if nums[i] > nums[max_idx]:
            max_idx = i

    ans = [nums[max_idx]]

    # 遍历并滑动窗口
    for i in range(k, len(nums)):
        if queue and queue[0] == i - k:
            queue.popleft()

        while queue and nums[queue[-1]] < nums[i]:
            queue.pop()

        queue.append(i)

        ans.append(nums[queue[0]])

    return ans