[LeetCode] 66. Plus One Java

题目：

Given a non-negative integer represented as a non-empty array of digits, plus one to the integer.

You may assume the integer do not contain any leading zero, except the number 0 itself.

The digits are stored such that the most significant digit is at the head of the list.

题意及分析：一个整数一数组形式展示，高位在前，整数加一之后仍然用数组表示，求数组。

代码：

class Solution {
    public int[] plusOne(int[] digits) {
        if(digits==null || digits.length==0) return digits;
        int[] res = new int[digits.length];
        digits[digits.length-1]++;
        int count = 0;
        int sum = 0;
        for(int i = digits.length-1;i>=0;i--){
            sum = count + digits[i];
            if(sum >= 10){
                res[i] = (sum) % 10;
                count = (sum) / 10;
            }else{
                res[i] = sum;
                count = 0;
            }
        }
        if(sum <10)
            return res;
        else{
            int[] a = new int[res.length+1];
            a[0] = 1;
            return a;
        }
    }
}