129. Find peak element
Given an array arr of integers. A peak element is defined as an element greater than both of its neighbors.
Formally, if arr[i] is the peak element, arr[i - 1] < arr[i] and arr[i + 1] < arr[i].
Find the index(0-based) of a peak element in the array. If there are multiple peak numbers, return the index of any peak number.
Note:
- As there can be many peak values, "true" is given as output if the returned index is a peak number, otherwise the returned value of index.
Example 1:
Input : arr = [1, 2, 3, 4, 5, 6, 7, 8, 5, 1]
Output: 7
Explanation: In this example, there is only 1 peak that is at index 7.
Example 2:
Input : arr = [1, 2, 1, 3, 5, 6, 4]
Output: 1
Explanation: In this example, there are 2 peak numbers at indices 1 and 5. We can consider any of them.
Now Your Turn!
Pick the correct output for the given inputInput : arr = [-2, -1, 3, 4, 5]
Still unsure what the problem is asking ?
Letās go through a few more examples, step by step, to make it clearer.
Constraints:
- Ā 1 <= arr.length <= 1000
- Ā -231 <= arr[i] <= 231 - 1
- Ā arr[i] != arr[i + 1] for all valid i.
- For arr[0], its left element can be considered as -ā
- For arr[n-1], its right element can be considered as -ā