Peak Index in a Mountain Array

Easy

Peak Index in a Mountain Array 題目

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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.