NYOJ A*B problem

 

http://acm.nyist.net/JudgeOnline/problem.php?pid=485

 

 

 
#include<stdio.h>
#include<string.h>

int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
     int s=0,i,j,ma,mb,a1[20]={0},b1[20]={0},c[40]={0};
     char a[20],b[20];
     scanf("%s %s",a,b);
     ma=strlen(a);
     mb=strlen(b);
     if((ma==1&&a[0]=='0')||(mb==1&&b[0]=='0'))
     printf("0\n");
     else
     {
     
     for(i=ma-1,j=0;i>=0;i--)
     a1[j++]=a[i]-'0';
     for(i=mb-1,j=0;i>=0;i--)
     b1[j++]=b[i]-'0';
    
    for(i=0;i<mb;i++)
    {
      for(j=0;j<ma;j++)
      c[i+j]+=a1[j]*b1[i];
    }
    for(i=0; i<39; i++) 
    {
        if(c[i]>=10) 
        {
            c[i+1]+=c[i]/10;
            c[i]%=10;
        }
    }

   
    for(i=0;i<39;i++)
    s+=c[i];
    s%=9;
    if(s==0)
    printf("9\n");
    else 
    printf("%d\n",s);
    } 
    }
    return 0;
}