Leetcode 400 Nth Digit - FirstSubmission - a few issues - failed test case: input: 10, output: 0, expected: 1

Leetcode400_NthDigit_FirstSubmission.cs

public class Solution {
    public int FindNthDigit(int n)  // 8, return 8 
        {
            var preprocessed = getPreprocessNumbers(); 

            var length = preprocessed.Count;

            /// there are 28 entries in the list
            for (int i = 0; i < length; i++ )
            {
                var current = preprocessed[i];

                if (n <= current[3]) // 8 < 9
                {
                    var start = i == 0 ? 1 : getStartByDigits(current[0]);  // 0 
                    var digits = current[0]; // 1
                    var sequence = (n - start) / digits; // 8                    
                    var nth = (n - start) % digits; // 0 

                    return getDigitInInteger(sequence, nth, digits);                   
                }
            }

            return 0; 
        }

        // 8  - start 1  sequence 7, nth 0, digits 1
        // 12 - start 10 sequence 1, nth 0, digits 2 
        // 13 - start 10 sequence 1, nth 1, digits 2
        private static int getDigitInInteger(int sequence, int nth, int digits)
        {
            int start = getStartByDigits(digits);
            start += sequence;

            int index = 0;
            int nthValue = 1;

            int current = start;
            int loops = digits - nthValue;
            int lastDigit = current % 10; 

            while (index < loops)
            {
                lastDigit = current % 10;
                current = current / 10; 
                index++;
            }

            return lastDigit;
        }

        private static int getStartByDigits(int digits)
        {
            return digits == 1 ? 1 : (int)Math.Pow(10, digits - 1);
        }

        /// <summary>
        /// 1    - 9,   1 digit number,  9   numbers,  9   * 1 digits in total
        /// 10   - 99,  2 digit numbers, 90  numbers,  90  * 2 digits in total
        /// 100  - 999, 3 digit numbers, 900 numbers,  900 * 3 digits in total
        /// 1000 - 9999, ...
        /// int 2^31
        /// </summary>
        /// <returns></returns>
        private static IList<int[]> getPreprocessNumbers()
        {
            var numbers = new List<int[]>();

            int start = 1;
            int max = int.MaxValue;            
            
            int digits = 1;
            int digitsUsed = 9;
            int numberCounts = 9;
            int totalDigitsUsed = 0;

            while (start <= max && ((long)totalDigitsUsed + (long)digitsUsed) < max)
            {
                totalDigitsUsed += digitsUsed;

                numbers.Add(new int[] { digits, numberCounts, digitsUsed, totalDigitsUsed });
                // ....
                start += numberCounts;

                // increment the variables
                digits++; // 1, 2, 3
                numberCounts *= 10;  // 9, 90, 900, ... 
                digitsUsed = numberCounts * digits; // 9, 90, 900, ...                              
            }

            return numbers;
        }
}