LeetCode 978. Longest Turbulent Subarray

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class Solution {
public:
    int maxTurbulenceSize(vector<int>& arr) {
        int n = arr.size();
        int preSign = 0, left = 0, right = 1, ans = 1;
        while (right < n) {
            int sign = arr[right] - arr[right - 1];
            if (sign == 0) {
                ans = max(ans, right - left);
                left = right;
            } else if ((sign > 0 && preSign > 0) || (sign < 0 && preSign < 0)) {
                ans = max(ans, right - left);
                left = right - 1;
            }
            preSign = sign;
            ++right;
        }
        return max(ans, right - left);
    }
};
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class Solution {
public:
    int maxTurbulenceSize(vector<int>& arr) {
        int n = arr.size();
        int up = 1, down = 1, ans = 1;
        for (int i = 0; i < n - 1; ++i) {
            if (arr[i + 1] > arr[i]) {
                up = down + 1;
                down = 1;
            } else if (arr[i + 1] < arr[i]) {
                down = up + 1;
                up = 1;
            } else {
                up = down = 1;
            }
            ans = max(ans, max(up, down));
        }
        return ans;
    }
};