66. Plus One

原题链接：https://leetcode.com/problems/plus-one/description/
这道题目自己花了二十分钟解出来了，看了下讨论区别人家的答案之后，感觉自己脑子上装的就是一坨屎:

import java.util.Arrays;

/**
 * Created by clearbug on 2018/2/26.
 */
public class Solution {

    public static void main(String[] args) {
        Solution s = new Solution();
        System.out.println(Arrays.toString(s.plusOne(new int[]{1, 2, 3, 4})));
        System.out.println(Arrays.toString(s.plusOne(new int[]{1, 2, 3, 4, 5})));
        System.out.println(Arrays.toString(s.plusOne(new int[]{4, 3, 2, 2})));
        System.out.println(Arrays.toString(s.plusOne(new int[]{1, 9, 9, 9})));
        System.out.println(Arrays.toString(s.plusOne(new int[]{9, 9, 9, 9})));

    }

    /**
     * 我的思路
     *
     * @param digits
     * @return
     */
    public int[] plusOne(int[] digits) {
        boolean carry = true;
        for (int i = digits.length - 1; i >= 0; i--) {
            if (carry) {
                if (digits[i] + 1 >= 10) {
                    carry = true;
                    digits[i] = digits[i] + 1 - 10;
                } else {
                    carry = false;
                    digits[i] = digits[i] + 1;
                }
            }
        }
        if (carry) {
            int[] res = new int[digits.length + 1];
            res[0] = 1;
            for (int i = 0; i < digits.length; i++) {
                res[i + 1] = digits[i];
            }
            return res;
        } else {
            return digits;
        }
    }

    /**
     * 官方讨论区的答案，看完之后真的发现自己很吃鲸😲
     *
     * @param digits
     * @return
     */
    public int[] plusOne2(int[] digits) {
        for (int i = digits.length - 1; i >= 0; i--) {
            if (digits[i] < 9) {
                digits[i]++;
                return digits;
            }
            digits[i] = 0;
        }

        int[] res = new int[digits.length + 1];
        res[0] = 1;
        return res;
    }

}