Problem Description
You are given an array of integers nums. Return the length of the longest subarray of nums which is either strictly increasing or strictly decreasing.
Key Insights
- A strictly increasing subarray requires each subsequent element to be greater than the previous one.
- A strictly decreasing subarray requires each subsequent element to be less than the previous one.
- We can iterate through the array and keep track of the current length of strictly increasing or decreasing sequences.
- Whenever we encounter a number that does not fit the current trend (increasing or decreasing), we reset the count and check if the previous count was the longest found so far.
Space and Time Complexity
Time Complexity: O(n), where n is the length of the input array nums. Each element is processed once.
Space Complexity: O(1), as we only use a few variables to store counts and maximum length.
Solution
The approach involves a single pass through the array while maintaining counters for the current lengths of increasing and decreasing subarrays. Whenever the trend changes (from increasing to decreasing or vice versa), we compare the current length to the maximum found so far and reset the counter for the new trend.