队列的最大值

队列的最大值

  1. Sliding Window Maximum

Hard

Given an array 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:

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Input: nums = [1,3,-1,-3,5,3,6,7], and 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

Note:
You may assume k is always valid, 1 ≤ k ≤ input array’s size for non-empty array.

Follow up:
Could you solve it in linear time?

涉及知识点:最小栈,如何用两个队列实现一个栈, 双端队列。

c++ deque基本操作

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void push_front(const T& x) //双端队列头部增加一个元素X
void push_back(const T& x) //双端队列尾部增加一个元素x
void pop_front() //删除双端队列中最前一个元素
void pop_back() //删除双端队列中最后一个元素
reference front() //返回首元素的引用
reference back() //返回尾元素的引用

解法1

解法2