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258. Add Digits【规律】

2024-09-10 18:52:02   207人阅读

2017/3/16 22:36:02

Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.

For example:

Given num = 38, the process is like: 3 + 8 = 11, 1 + 1 = 2. Since 2 has only one digit, return it.

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

 
版本1    循环
  1. publicclassSolution{
  2. publicint addDigits(int num){
  3. while( num /10!=0)
  4. num = num/10+ num%10;
  5. return num;
  6. }
  7. }
 
版本2   列出表格观察，发现9个数字一循环的规律，一行代码就搞定。
技术分享
  1. publicclassSolution{
  2. publicint addDigits(int num){
  3. return num %9==0? num ==0?0:9: num%9;
  4. }
  5. }
 

258. Add Digits【规律】


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