[LeetCode] Longest Mountain in Array 数组中最长的山

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Let‘s call any (contiguous) subarray B (of A)?a?mountain?if the following properties hold:

• B.length >= 3
• There exists some?0 < i?< B.length - 1?such that?B[0] < B[1] < ... B[i-1] < B[i] > B[i+1] > ... > B[B.length - 1]

(Note that B could be any subarray of A,including the entire array A.)

Given an array?A?of integers,?return the length of the longest?mountain.?

Return?0?if there is no mountain.

Example 1:

Input: [2,1,4,7,3,2,5]
Output: 5
Explanation: The largest mountain is [1,2] which has length 5.

Example 2:

Input: [2,2]
Output: 0
Explanation: There is no mountain.

Note:

1. 0 <= A.length <= 10000
2. 0 <= A[i] <= 10000

Follow up:

• Can you solve it using only one pass?
• Can you solve it in?O(1)?space?

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参考资料：

https://leetcode.com/problems/longest-mountain-in-array/