2762. Continuous Subarrays

public class Solution
{
    public long ContinuousSubarrays(int[] nums)
    {
        long ans = 1; // [nums[0]]
        int left = nums[0] - 2;
        int right = nums[0] + 2;
        int l = 0;

        // nums[l..r] is a valid window with range in [left, right].
        for (int r = 1; r < nums.Length; r++)
        {
            if (left <= nums[r] && nums[r] <= right)
            {
                left = Math.Max(left, nums[r] - 2);
                right = Math.Min(right, nums[r] + 2);
            }
            else
            {
                // nums[r] is out-of-bounds, so reconstruct the window.
                left = nums[r] - 2;
                right = nums[r] + 2;
                l = r;
                // If we consistently move leftward in each iteration, it implies that
                // the entire left subarray satisfies the given condition. For every
                // subarray with l in the range [0, r], the condition is met, preventing
                // the code from reaching the final "else" condition. Instead, it stops
                // at the "if" condition.
                while (nums[r] - 2 <= nums[l] && nums[l] <= nums[r] + 2)
                {
                    left = Math.Max(left, nums[l] - 2);
                    right = Math.Min(right, nums[l] + 2);
                    --l;
                }
                ++l;
            }
            // nums[l..r], nums[l + 1..r], ..., nums[r]
            ans += r - l + 1;
        }

        return ans;
    }
}