队列的最大值

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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