Leetcode852. Peak Index in a Mountain Array
Let's call an array?arr
?a?mountain?if the following properties hold:
arr.length >= 3
There exists some?
i
?with?0 < i?< arr.length - 1
?such that:arr[0] < arr[1] < ... arr[i-1] < arr[i]
arr[i] > arr[i+1] > ... > arr[arr.length - 1]
Given an integer array?arr
?that is?guaranteed?to be?a mountain, return any?i
?such that?arr[0] < arr[1] < ... arr[i - 1] < arr[i] > arr[i + 1] > ... > arr[arr.length - 1]
.
?
Example 1:
Input: arr = [0,1,0]Output: 1
Example 2:
Input: arr = [0,2,1,0]Output: 1
Example 3:
Input: arr = [0,10,5,2]Output: 1
?
Constraints:
3 <= arr.length <= 104
0 <= arr[i] <= 106
arr
?is?guaranteed?to be a mountain array.
Success
Details?
Runtime:?1 ms, faster than?15.14%?of?Java?online submissions for?Peak Index in a Mountain Array.
Memory Usage:?45.8 MB, less than?19.80%?of?Java?online submissions for?Peak Index in a Mountain Array.