problem0852

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852. Peak Index in a Mountain Array

题目

Let's call an array A a mountainif 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 anyisuch thatA[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. Ais a mountain, as defined above.

解题思路

见程序注释