845

 1 class Solution:
 2     def longestMountain(self, A: List[int]) -> int:
 3         n = len(A)
 4         left = [0] * n  # 初始化
 5         for i in range(1, n):
 6             left[i] = (left[i - 1] + 1 if A[i - 1] < A[i] else 0)
 7 
 8         right = [0] * n
 9         for i in range(n - 2, -1, -1):  # 倒着遍历的
10             right[i] = (right[i + 1] + 1 if A[i] > A[i + 1] else 0)
11 
12         ans = 0
13         for i in range(n):
14             if left[i] > 0 and right[i] > 0:
15                 ans = max(ans, left[i] + right[i] + 1)
16 
17         return ans