uva : 446 - Kibbles "n" Bits "n" Bits "n" Bits

#include<stdio.h>
#include<string.h>
int main()
{
    char a[20][5]={"0000","0001","0010","0011","0100","0101","0110","0111","1000","1001","1010","1011","1100","1101","1110","1111"};
    char b[20]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
    long test;
    scanf("%ld",&test);
    while(test!=0)
    {
        char d[100]="0",c[20],e[100]="0",ch,f[100];
        int i,j,k,l,m,n,sum1=0,sum2=0,sum3;
        scanf("%s %c %s",&c,&ch,&f);
        if(strlen(c)==1)
        {
            strcat(e,"00000000");
            for(i=0;i<16;i++)
            {
                if(b[i]==c[0])
                {
                    strcat(e,a[i]);
                    break;
                }
            }
        }
       else if(strlen(c)==2)
        {
            strcat(e,"0000");
            for(j=0;j<2;j++)
            {
                for(i=0;i<16;i++)
                {
                    if(c[j]==b[i])
                    {
                        strcat(e,a[i]);
                        break;
                    }
                }
            }
        }
        else
        {
            for(j=0;j<3;j++)
            {
                for(i=0;i<16;i++)
                {
                    if(c[j]==b[i])
                    {
                        strcat(e,a[i]);
                        break;
                    }
                }
            }
        }
        if(strlen(f)==1)
        {
            strcat(d,"00000000");
            for(i=0;i<16;i++)
            {
                if(b[i]==f[0])
                {
                    strcat(d,a[i]);
                    break;
                }
            }
        }
       else if(strlen(f)==2)
        {
            strcat(d,"0000");
            for(j=0;j<2;j++)
            {
                for(i=0;i<16;i++)
                {
                    if(f[j]==b[i])
                    {
                        strcat(d,a[i]);
                        break;
                    }
                }
            }
        }
        else
        {
            for(j=0;j<3;j++)
            {
                for(i=0;i<16;i++)
                {
                    if(f[j]==b[i])
                    {
                        strcat(d,a[i]);
                        break;
                    }
                }
            }
        }
        for(i=0;i<strlen(e);i++)
        {
            sum1=sum1*2+(e[i]-48);
        }
        for(i=0;i<strlen(d);i++)
        {
            sum2=sum2*2+(d[i]-'0');
        }
        if(ch=='+')sum3=sum1+sum2;
        else sum3=sum1-sum2;
        printf("%s %c %s = %d\n",e,ch,d,sum3);
        test--;
    }
    return 0;
}