题目描述

题目链接：66. Plus One

Given a non-empty array of digits representing a non-negative integer, increment 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 contains a single digit.

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

例子

例子 1

Input: digits = [1,2,3] Output: [1,2,4] Explanation: The array represents the integer 123.

例子 2

Input: digits = [4,3,2,1] Output: [4,3,2,2] Explanation: The array represents the integer 4321.

例子 3

Input: digits = [0] Output: [1]

Constraints

• 1 <= digits.length <= 100
• 0 <= digits[i] <= 9

解题思路

从后往前依次加一，遇到有一次没有进位时直接退出循环。推出循环后判断最后一位有无进位，有则在数组头加一即可，代码如下：

#include <vector>

class Solution {
public:
    std::vector<int> plusOne(std::vector<int>& digits) {
        bool flag = true;
        for (int i = digits.size() - 1; i >= 0; i--) {
            if (!flag) break;
            flag = false;
            digits[i]++;
            if (digits[i] == 10) {
                digits[i] = 0;
                flag = true;
            }
        }
        if (flag) {
            digits.insert(digits.begin(), {1});
        }
        return digits;
    }
};

• 时间复杂度: O(n)
• 空间复杂度: O(1)

GitHub 代码同步地址： 66.PlusOne.cpp

其他题目： GitHub: Leetcode-C++-Solution 博客： Leetcode-Solutions