LeetCode Plus One

[code]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.

[code]public class Solution {
    public int[] plusOne(int[] arr) {
        if(arr[arr.length - 1] != 9)
        {
                arr[arr.length - 1] += 1;
                return arr;
        }
        else
        {
            for(int index =arr.length - 1;index >= 0;index--)
            {

                if(arr[index] != 9)
                {
                    arr[index] += 1;
                    for(int i = index+1;i<arr.length;i++)
                        arr[i] = 0;

                    return arr;
                }
                    if(index == 0)
                {
                    int [] res = new int[arr.length+1];
                    for(int j = arr.length;j>=1;j--)
                    {
                        res[j] = 0;
                    }
                    res[0] = 1;
                    return res;
                }
            }
        }
        return arr;
    }
}