Peak Finder in an Array

ArrayBinary Search

Given a non-empty array of integers, find any peak element. An element is considered a peak if it is greater than its neighbors. Note that an element at index 0 or at the last index of the array is considered a peak if it is greater than its one neighbor.

Example 1

Input

[
  1,
  3,
  20,
  4,
  1,
  0
]

Output

Explanation. 20 is a peak element because it is greater than both of its neighbors (3 and 4).

Example 2

Input

Output

Explanation. 20 is a peak element because it is greater than its left neighbor (10) and has no right neighbor.

Example 3

Input

[
  10,
  5,
  2
]

Output

Explanation. 10 is a peak at the start of the array as it is only compared with its right neighbor.

Example 4

Input

[
  6,
  6,
  6,
  6
]

Output

Explanation. Here, any 6 can be considered a peak since all elements are the same and adjacent comparison holds true.

Follow-up: Can you implement your solution in a way that achieves O(log n) time complexity?

Constraints:

The input array will contain at least one element and will contain only integers.

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Acceptance Rate: 50.0%
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