题解 | 求峰谷点数

class Solution:
    def countPeakPoint(self , a: List[int]) -> int:
        a = [a[0]] + a + [a[len(a) - 1]]
        n = len(a)
        cnt = 0
        for i in range(1, n):
            if a[i - 1] < a[i] > a[i + 1] or a[i - 1] > a[i] < a[i + 1]:
                cnt += 1
        return cnt