Given a non-empty array of digits representing a non-negative integer, plus one to the integer.The digits are stored such that the most significant digit is at the head of the list, and each element in the array contain a single digit.You may assume the integer does not contain any leading zero, except the number 0 itself.Example 1:Input: [1,2,3]Output: [1,2,4]Explanation: The array represents the integer 123.Example 2:Input: [4,3,2,1]Output: [4,3,2,2]Explanation: The array represents the integer 4321.难度：easy题目：给定一个由单个数字组成的非空数组来表示一个整数，为这个整数加上1.数字的存储方式使得最有效数字位于列表的开头，数组中的每个元素都包含一个数字。假定数组组成的整数不以0开头，除了数字0本身。思路：找出第一个非9的数字加1返回。如果为9置0继续。Runtime: 0 ms, faster than 100.00% of Java online submissions for Plus One.Memory Usage: 26.4 MB, less than 42.73% of Java online submissions for Plus One.class Solution { public int[] plusOne(int[] digits) { for (int i = digits.length - 1; i >= 0; i–) { if (digits[i] < 9) { digits[i] += 1; return digits; } else { digits[i] = 0; } } if (0 == digits[0]) { int[] result = new int[digits.length + 1]; result[0] = 1; for (int i = 0; i < digits.length; i++) { result[i + 1] = digits[i]; } return result; } return new int[0]; }}