258. Add Digits · Hsing-Yu

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題目敘述

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

解題思路

Solution

class Solution {
    public int addDigits(int num) {
        
        while(num >= 10){
            String str = Integer.toString(num);
            num = 0;
            for(int i = 0; i < str.length(); i++){
                num += Integer.parseInt(str.substring(i, i + 1));
            }
        }

        return num;
    }
}