import java.util.ArrayList;import java.util.Arrays;import java.util.List;/** * Source : https://oj.leetcode.com/problems/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 PlusOne {    /**     * 加法运算，注意进位     *     * @param digit     * @return     */    public Integer[] plusOne (int[] digit) {        int carry = 1;        List
    
      result = new ArrayList
     
      ();        for (int i = digit.length - 1; i > -1; i--) {            carry += digit[i];            result.add(0, carry % 10);            carry = carry / 10;        }        if (carry > 0) {            result.add(0, carry);        }        return result.toArray(new Integer[result.size()]);    }    public static void main(String[] args) {        PlusOne plusOne = new PlusOne();        int[] arr = new int[]{1,2,3};        int[] arr1 = new int[]{1,9,9};        int[] arr2 = new int[]{9,9,9};        int[] arr3 = new int[]{1};        int[] arr4 = new int[]{9};        int[] arr5 = new int[]{};        System.out.println(Arrays.toString(plusOne.plusOne(arr)));        System.out.println(Arrays.toString(plusOne.plusOne(arr1)));        System.out.println(Arrays.toString(plusOne.plusOne(arr2)));        System.out.println(Arrays.toString(plusOne.plusOne(arr3)));        System.out.println(Arrays.toString(plusOne.plusOne(arr4)));        System.out.println(Arrays.toString(plusOne.plusOne(arr5)));    }}