Digital Roots (题目虽水，解法不可水)

最新推荐文章于 2024-05-04 20:05:41 发布

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本文介绍了一种计算数字根的方法，即通过不断累加整数的各位数字直至结果为单一位数的过程，并提供了一个简单的C语言程序实现。

Digital Roots

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 42315 Accepted Submission(s): 13085

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

Sample Output

6
3

题目出自http://acm.hdu.edu.cn/showproblem.php?pid=1013

#include <stdio.h>

int main()
{
    int sum=0;
    char a;

    while(a=getchar())//数据很大，用字符处理
    {
        if(a=='\n')
        {
            if(!sum) return 0;
            printf("%d\n",sum%9?sum%9:9); //把所有位数的数字相加，然后 mod 9 可得
            sum=0;
        }
        else if(a>='0' && a<='9')
        {
            sum+=a-'0';
        }
    }

    return 0;
}