LeetCode 66: Plus One

Given a non-negative number represented as an array of digits, plus one to the number.
The digits are stored such that the most significant digit is at the head of the list.

public class Solution {
    public int[] plusOne(int[] digits) {
        // Consider a special case that should change the dimension of result (digits = {9,9,9,...})
        int n = digits.length;
        boolean allNine = true;
        
        for (int i = 0; i < n; i++)
            if (digits[i] != 9)
            {
                allNine = false;
                break;
            }
            
        if (allNine)
        {
            int[] result = new int[n+1];
            result[0] = 1;
            return result;
        }
        else
        {
            int[] result = new int[n];
            int i, j;
            
            for (i = n-1; i >= 0; i--)
                if (digits[i] == 9)
                    result[i] = 0;
                else
                {
                    result[i] = digits[i]+1;
                    break;
                }
                
            for (j = i-1; j >= 0; j--)
                result[j] = digits[j];
                
            return result;
        }
    }
}