713 Adding Reversed Numbers

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

#define MAX 300


void reverse(char *fnum,char *snum)
{
    int len,i;
    len=strlen(fnum);
    for(i=0;i<len;i++)
    snum[i]=fnum[len-i-1];
    snum[len]='\0';
}

void add(char *first,char *sec,char *result)
{
    char F[MAX],S[MAX],R[MAX];
    int flen,slen,now,extra,sum;
    flen=strlen(first);
    slen=strlen(sec);
    reverse(first,F);
    reverse(sec,S);
    for(now=0,extra=0;(now<flen&&now<slen);now++)
    {
    sum=(F[now]-'0')+(S[now]-'0')+extra;
    R[now]=sum%10+'0';
    extra=sum/10;
    }
    for(;now<flen;now++)
    {
     sum=F[now]+extra-'0';
    R[now]=sum%10+'0';
    extra=sum/10;

    }

     for(;now<slen;now++)
    {
     sum=S[now]+extra-'0';
    R[now]=sum%10+'0';
    extra=sum/10;

    }
    if(extra!=0)
    R[now++]=extra+'0';
    R[now]='\0';
    if(strlen(R)==0)
    strcpy(R,"0");
    reverse(R,result);

}

int main()
{
    char f[MAX],s[MAX],r[MAX],f1[MAX],s1[MAX];
    int i,len,t,flag;
    scanf("%d",&t);
    while(t--)
    {
    scanf("%s%s",&f1,&s1);
    reverse(f1,f);
    reverse(s1,s);
    add(f,s,r);
    len=strlen(r);
    flag=0;
    for(i=len-1;i>=0;i--)
    {
        if((r[i]==48)&&(flag==0));
        else
       {printf("%c",r[i]);
        flag=1;
       }
    }
    printf("\n");

    }
    return 0;
}