题解 | 最长山脉

#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param nums int整型一维数组 
# @return int整型
#
class Solution:
    def longestmountain(self , nums: List[int]) -> int:
        # write code here
        n = len(nums)
        l, r = [1]*n, [1]*n
        for i in range(1,n):#从左开始数山脉
            if nums[i]>nums[i-1]:
                l[i] = l[i-1]+1
        for i in range(n-2,-1,-1):#从右开始数山脉
            if nums[i]>nums[i+1]:
                r[i] = r[i+1]+1
        ans = 0
        for i in range(n):#山脉左边数+山脉右边数-1
            if l[i]+r[i]-1>ans:
                ans = l[i]+r[i]-1
        return ans if ans>=3 else 0#大于等于3返回山脉数，否则返回0