ACM_1115_String,Char,int类型转换，递归思想

题目：

Background

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.

Example

Input

24390

Output

63

import java.util.Scanner;public class ACM_1115 {/** * @param args */public static void main(String[] args) {// TODO Auto-generated method stubScanner s = new Scanner(System.in);String num = s.nextLine();// see if a String is equal to 0 or notwhile (!num.equals("0")){int root_value = Get_root_value(num);System.out.println(root_value);num = s.nextLine();}}private static int Get_root_value(String num){int sum = 0;for(int i=0;i<num.length();i++){//get the char in the string at index i//convert char into intsum += (int)(num.charAt(i) - '0');}if(sum >= 10){//convert integer to Stringreturn Get_root_value( Integer.toString(sum) );}return sum;}}

summary：

1.判断string变量是否为“0“

num.equals("0")

注意：不能用==“0”判断

2. 从string中取字符，并转换成int类型

(int)(num.charAt(i) - '0')

3.将整数转化为string类型

Integer.toString(sum) 

4.文章思路

以string的方式存取输入，而不是int，因为int有bit数限制，而string没有bit限制