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 ){
        digits[digits.length-1]++;
        int i;
        for( i=digits.length-1; i>0 && digits[i]/10 != 0; i-- ){
            digits[i-1] += digits[i]/10;
            digits[i] = digits[i] % 10;
        }
        int[] res = null;
        int k;    //the start point of res to copy from digits
        if( digits[i]/10!=0 ){
            res = new int[ digits.length + 1 ];
            res[0] = digits[i] / 10;
            digits[i] = digits[i] % 10;
            k = 1;
        }
        else{
            res = new int[ digits.length ];
            k = 0;
        }
        System.arraycopy(digits, 0, res, k, digits.length);
        return res;
    }
}