258.add-digits

Statement

简体中文English

Metadata

• Link: 各位相加
• Difficulty: Easy
• Tag: 数学 数论 模拟

给定一个非负整数 num，反复将各个位上的数字相加，直到结果为一位数。返回这个结果。

 

示例 1:

输入: num = 38
输出: 2 
解释: 各位相加的过程为：
38 –> 3 + 8 –> 11
11 –> 1 + 1 –> 2
由于 2 是一位数，所以返回 2。

示例 1:

输入: num = 0
输出: 0

 

提示：

• 0 <= num <= 231 - 1

 

进阶：你可以不使用循环或者递归，在 O(1) 时间复杂度内解决这个问题吗？

Metadata

• Link: Add Digits
• Difficulty: Easy
• Tag: Math Number Theory Simulation

Given an integer num, repeatedly add all its digits until the result has only one digit, and return it.

 

Example 1:

Input: num = 38
Output: 2
Explanation: The process is
38 –> 3 + 8 –> 11
11 –> 1 + 1 –> 2 
Since 2 has only one digit, return it.

Example 2:

Input: num = 0
Output: 0

 

Constraints:

• 0 <= num <= 231 - 1

 

Follow up: Could you do it without any loop/recursion in O(1) runtime?

Solution

Python 3

class Solution:
    def addDigits(self, num: int) -> int:
        return (num - 1) % 9 + 1 if num > 0 else 0

---

最后更新: October 11, 2023