[LeetCode]#852. Peak Index in a Mountain Array

Environment: Python 3.7

Key technique: index.max() function

Let’s call an array A a mountain if the following properties hold:

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

Given an array that is definitely a mountain, return any i such that A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1].

Example 1:

Input: [0,1,0]
Output: 1

Example 2:

Input: [0,2,1,0]
Output: 1

Note:

1. 3 <= A.length <= 10000
2. 0 <= A[i] <= 10^6
3. A is a mountain, as defined above.

Analysis:

Assume peak is maximum value in list and use index.max() function to find location.

Solution:

class Solution:
    def peakIndexInMountainArray(self, A):
        ans=A.index(max(A))
        
        return ans

Submitted result:

Reference:

https://nifannn.github.io/2018/06/29/%E7%AE%97%E6%B3%95%E7%AC%94%E8%AE%B0-Leetcode-852-Peak-Index-in-a-Mountain-Array/