杭电acm2057

http://acm.hdu.edu.cn/showproblem.php?pid=2057

十六进制转成十进制，加减后再转成十六进制输出。。。。。转成的十进制太大，用__int64

#include<stdio.h>
#include<string.h>
__int64 zhuan(char *s)
{
    __int64 i=0,sum=0;
    if(s[i]=='-'||s[i]=='+')
      i++;
    while(s[i])
    {
       if(s[i]>='0'&&s[i]<='9')
         sum=(s[i]-'0')+sum*16;
       else sum=(s[i]-'A'+10)+sum*16;
       i++;
    }
    if(s[0]=='-')
       return (-sum);
    return sum;
}
void hui(__int64 n,char *s)
{
   __int64 i=0,j=0,a[100],k;
   while(n/16)
   {
      a[i++]=n%16;
      n/=16;
   }
   a[i++]=n;
   while(i--)
   {
       if(a[i]>9)
       s[j++]=a[i]-10+'A';
       else s[j++]=a[i]+'0';
   }
   s[j]=0;
}
int main()
{
   __int64 i,j,flag,a,b,sum;
   char aa[20],bb[20],ans[20];
   while(scanf("%s %s",aa,bb)!=EOF)
   {
       a=zhuan(aa);
       b=zhuan(bb);
       sum=a+b;
       if(sum>=0)
       flag=1;
       else {
            flag=-1;
            sum=-sum;
            }
       if(flag==-1)
         printf("-");
       hui(sum,ans);
       printf("%s\n",ans);
   }
   return 0;
}