1409232238-hd-Digital Roots

Digital Roots

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

Total Submission(s): 1080    Accepted Submission(s): 447

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 题目大意        给你一个数，如果其不是个位数，就把他的每一位相加，然后再判断。 错误原因        没有考虑到给出的数有可能超出int范围，所以当代码OK之后出现了WA，要注意从给定数据的范围考虑，这点很容易忽略。 代码 <span style="font-size:18px;">#include<stdio.h> #include<string.h> char s[1100]; int main() { int i,j; int sum,len; while(gets(s)&&strcmp(s,"0")!=0) { len=strlen(s); sum=0; for(i=0;i<len;i++) sum+=s[i]-'0'; while(sum/10>0) { j=0; while(sum!=0) { j+=sum%10; sum/=10; } sum=j; } printf("%d\n",sum); } return 0; } </span>