0407. Plus One

public class Solution {
    /**
     * @param digits: a number represented as an array of digits
     * @return: the result
     */
    public int[] plusOne(int[] digits) {
        int length = digits.length;
        if(digits[length-1] != 9){
            digits[length-1]++;
            return digits;
        }
        for(int i = digits.length-1; i >= 0; i--){  //units digits is 9
            if(digits[i] == 9){
                digits[i] = 0;
            }
            else{
                digits[i]++;
                return digits;
            }
        }
        int[] result = new int[digits.length + 1];  //power of 10
        result[0] = 1;
        for(int i = 0; i < digits.length; i++){
            result[i+1] = digits[i];
        }
        return result;
    }
}