我们把符合下列属性的数组 A 称作山脉:
A.length >= 3
存在 0 < i < A.length - 1 使得A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1]
给定一个确定为山脉的数组,返回满足 A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1] 的 i 的值。
思路:就是二分查找找最大值点
class Solution(object):
def peakIndexInMountainArray(self, A):
"""
:type A: List[int]
:rtype: int
"""
left = 0
right = len(A)
while(left < right):
mid = int((left + right) / 2)
if A[mid-1] < A[mid] < A[mid + 1]:
left = mid
elif A[mid-1] > A[mid] > A[mid + 1]:
right = mid
elif A[mid] > A[mid-1] and A[mid] > A[mid+1]:
return mid