杭電oj-1013-java

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int result=0;
		List<Integer> aList=new ArrayList(); 
		while (true) {			
			int n=sc.nextInt();						
			if (n==0) {
				break;
			}
			result=dg(n);
			aList.add(result);
		}		
		for(int i:aList) {
			System.out.println(i);
		}		
	}
	private static int dg(int n) {	
		 List<Integer> list=new ArrayList<>();
		 puttolist(n,list);
		 int sum=0;
		 for(int i:list) {
			sum+=i;
		}
		if (sum>=10) {
			return dg(sum);
		} else {
			return sum;
		}
	}
	private static void puttolist(int n, List<Integer> list) {		
		 if(n>=1&&n<=9) {
				list.add(n);
				return;
			}
		 int p=n%10;
		 n=(n-n%10)/10;
		 list.add(p);
		 puttolist(n, list);
	}	
}
           

經過自己的努力，終于ac啦

Digital Roots

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)

Total Submission(s): 106224    Accepted Submission(s): 32874

Problem Description The digital root of a positive integer is found by summing the digits of the integer. If the resulting value is a single digit then that digit is the digital root. If the resulting value contains two or more digits, those digits are summed and the process is repeated. This is continued as long as necessary to obtain a single digit.

For example, consider the positive integer 24. Adding the 2 and the 4 yields a value of 6. Since 6 is a single digit, 6 is the digital root of 24. Now consider the positive integer 39. Adding the 3 and the 9 yields 12. Since 12 is not a single digit, the process must be repeated. Adding the 1 and the 2 yeilds 3, a single digit and also the digital root of 39.  

Input The input file will contain a list of positive integers, one per line. The end of the input will be indicated by an integer value of zero.  

Output For each integer in the input, output its digital root on a separate line of the output.  

Sample Input

24 39 0  

Sample Output

6 3  

Source Greater New York 2000  

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