Longest Peak
Write a function that takes in an array of integers and returns the length of the longest peak in the array.
A peak is defined as adjacent integers in the array that are strictly increasing until they reach a tip (the highest value in the peak), at which point they become strictly decreasing. At least three integers are required to form a peak.
For example, the integers 1, 4, 10, 2 form a peak, but the integers 4, 0, 10 don't and neither do the integers 1, 2, 2, 0. Similarly, the integers 1, 2, 3 don't form a peak because there aren't any strictly decreasing integers after the 3.
array = [1, 2, 3, 3, 4, 0, 10, 6, 5, -1, -3, 2, 3]
Sample Output
6 // 0, 10, 6, 5, -1, -3
Hints
Hint 1
You can solve this question by iterating through the array from left to right once.
Hint 2
Iterate through the array from left to right, and treat every integer as the potential tip of a peak. To be the tip of a peak, an integer has to be strictly greater than its adjacent integers. What can you do when you find an actual tip?
Hint 3
As you iterate through the array from left to right, whenever you find a tip of a peak, expand outwards from the tip until you no longer have a peak. Given what peaks look like and how many peaks can therefore fit in an array, realize that this process results in a linear-time algorithm. Make sure to keep track of the longest peak you find as you iterate through the array.
Optimal Space & Time Complexity
O(n) time | O(1) space - where n is the length of the input array