leetcode -- 66. Plus One

题目描述

题目难度：Easy
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.

AC代码1

class Solution {
    public int[] plusOne(int[] digits) {
        int len = digits.length;
        int carry = 1, tmp = 0;
        int[] res = digits;
        for(int i = len - 1; i >= 0; i--){
            tmp = carry;
            carry = (digits[i] + tmp) / 10;
            digits[i] = (digits[i] + tmp) % 10;
        }
        if(carry != 0){
            res = new int[len + 1];
            res[0] = carry;
            for(int i = 0;i < len;i++) res[i + 1] = digits[i];
        }
        return res;
    }
}

AC代码2

大神的代码，经过了优化，很优秀。

public class Solution {
    public int[] plusOne(int[] digits) {
        for(int i = digits.length - 1;i >= 0;i--){
			if(digits[i] < 9){
				digits[i]++;
				return digits;
			}
			digits[i] = 0;
		}
		int[] temp = new int[digits.length + 1];
		temp[0] = 1;
		return temp;
    }
}