LeetCode 978: Longest Turbulent Subarray Solution

Master LeetCode problem 978 (Longest Turbulent Subarray), a medium challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.

978. Longest Turbulent Subarray

Medium

Array Dynamic Programming Sliding Window

Problem Explanation

Explanation

To solve this problem, we can iterate through the array and keep track of the current turbulent subarray's length. We will maintain two variables: up to track the length of the current increasing subarray ending at the current index, and down to track the length of the current decreasing subarray ending at the current index. We will update these variables based on the comparison of the current element with the previous one.

At each step, we update the length of the turbulent subarray by taking the maximum of up and down and then reset the appropriate variable based on the comparison of the current element with the previous one.

Finally, we return the maximum turbulent subarray length found during the iteration.

Time complexity: O(n) where n is the number of elements in the input array. Space complexity: O(1)

Solution Code

class Solution {
    public int maxTurbulenceSize(int[] arr) {
        int n = arr.length;
        int up = 1, down = 1, maxLen = 1;

        for (int i = 1; i < n; i++) {
            if (arr[i - 1] < arr[i]) {
                down = up + 1;
                up = 1;
            } else if (arr[i - 1] > arr[i]) {
                up = down + 1;
                down = 1;
            } else {
                up = 1;
                down = 1;
            }

            maxLen = Math.max(maxLen, Math.max(up, down));
        }

        return maxLen;
    }
}

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