HDU 1002 大整数相加

#include<stdio.h>
#include<string.h>
int main()
{
char a[1000],b[1000],c[1001];
int i,j=1,p=0,n,n1,n2;
scanf("%d",&n);
while(n)
{
scanf("%s %s",a,b);
printf("Case %d:\n",j);
printf("%s + %s = ",a,b);
n1=strlen(a)-1;
n2=strlen(b)-1;
for(i=0; n1>=0 || n2>=0; i++,n1--,n2--)
{
if(n1>=0 && n2>=0){c[i]=a[n1]+b[n2]-'0'+p;}
if(n1>=0 && n2<0){c[i]=a[n1]+p;}
if(n1<0 && n2>=0){c[i]=b[n2]+p;}
p=0;
if(c[i]>'9'){c[i]=c[i]-10;p=1;}
}
if(p==1){printf("%d",p);}
while(i--)
{printf("%c",c[i]);}
j++;
if(n!=1){printf("\n\n");}
else {printf("\n");}
n--;
}
}