问题描述：
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.
分析：非负整数，存储在数组中。the most significant digit 最高位存储在列表的第一个，例如：98, array[0] 存储9，array[1]存储8。
原文：http://www.cnblogs.com/mydesky2012/p/5051599.html