题目：

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.

思路：

• 题意是用一个数组来表示一个非负的整数。范围是0~9的数字，模拟一个加法的加一操作
• 推断是否进位。假设是9，加1就是10，置为0，然后进位。
• 假设超除了界限，又一次设置一个数组，第一位是1。后面是0 -

代码：

public class Solution {    public int[] plusOne(int[] digits) {         int carries = 1;        for(int i = digits.length-1; i>=0 && carries > 0; i--){  // fast break when carries equals zero            int sum = digits[i] + 1;            digits[i] = sum % 10;            carries = sum / 10;        }        if(carries == 0)            return digits;        int[] rst = new int[digits.length+1];        rst[0] = 1;        for(int i=1; i< rst.length; i++){            rst[i] = 0;        }        return rst;    }}