# Leetcode 162 - Find peak element

`Note:`

- By the description, we need to use
`binary search`

. - But the array is not sorted, how should we know which direction we need to move?
- Always move toward the element with
`bigger value`

! - Imagine we always do this, eventually when we hit
`0`

or`len - 1`

, both`nums[-1]`

or`nums[len]`

are`-Infinity`

. We can definitely get`nums[i]`

bigger than its neighbors.

`Question:`

A peak element is an element that is `strictly greater`

than its neighbors.

Given an integer array nums, find a peak element, and return its index. If the array contains multiple peaks, return the index to any of the peaks.

You may imagine that nums[-1] = nums[n] = -∞.

You must write an algorithm that runs in `O(log n)`

time.

`Example:`

1 | Input: nums = [1,2,3,1] |

`Code:`

1 | /** |