## SGU 118 解题报告

http://acm.sgu.ru/problem.php?contest=0&problem=118

## 118. Digital Root

time limit per test: 0.50 sec.
memory limit per test: 4096 KB

Let f(n) be a sum of digits for positive integer n. If f(n) is one-digit number then it is a digital root for n and otherwise digital root of n is equal to digital root of f(n). For example, digital root of 987 is 6. Your task is to find digital root for expression A1*A2*…*AN + A1*A2*…*AN-1 + … + A1*A2 + A1.

### Input

Input file consists of few test cases. There is K (1 <=K <= 5) in the first line of input. Each test case is a line. Positive integer number N is written on the first place of test case (N<=1000). After it there are N positive integer numbers (sequence A). Each of this numbers is non-negative and not more than 109.

### Output

Write one line for every test case. On each line write digital root for given expression.

1
3 2 3 4

5

### CODE

#include
int main()
{
int k,n,x,t,sum;
scanf("%d",&k);
while(k--)
{
sum=0;
t=1;
scanf("%d",&n);
while(n--)
{
scanf("%d",&x);
x%=9;
t*=x;
t%=9;
sum+=t;
sum%=9;
}
if(sum==0) sum=9;
printf("%dn",sum);
}
return 0;
}