ZOJ 1115 解题报告

Digital Roots

---

Time Limit: 1 Second      Memory Limit: 32768 KB

---

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

      1.首先没有考虑到这个整数会是很大一个数所以不能单纯用个int型保存，只能用到数组，这是WA的主要原因。

      2.用到了一个原理就是一个整数的所有位数之和对9取余等于该数对9取余。

#include <iostream>#include <string>using namespace std;int main(){string str;while(cin>>str&&str[0]!='0'){int result=0;for(int i=0;i<str.length();i++){result+=str[i]-'0';}result=result%9;if (result==0){result=9;}cout<<result<<endl;}return 0;}