i need help. my code is running correctly. but when i try to print the sum of k-number, it gives wrong answer..

int main()
{
int l,r,k,i,sum=0;

scanf("%d%d%d",&l,&r,&k);
for(i=l;i<=r;i++)
{   

    int x=i,cnt=0,a=k,b,c=i,d=0,e,f=i,g,w;

    while(x!=0)
    {
        cnt++;
        x=x/10;

    }

    if(cnt<=k)
    {
        sum=sum+i;

    }


    else
    {
        while(a!=0)
        {
            b=c%10;
            d=d+b;
            a--;
            c=c/10;
        }

        while(cnt!=0)
        {
            if(cnt<=k)
            {
                e=f%10;
                g=g+e;  
            }
            f=f/10;
            cnt--;
        }



        if(d==g)
        {
            sum=sum+i;
        }
    }
}

printf("%d",sum);   /*when i include this line in my code,                          it will give wrong answer.*/
return 0;
}

not able to minimize the running time. plz help....

include

include

include

include

include

using namespace std;

int main() { /* Enter your code here. Read input from STDIN. Print output to STDOUT */
long long int L,R,i,sum=0; int sum1,sum2,n,x,k,j,t; int a[18];
cin>>L>>R>>k; for(i=L;i<=R;i++) { j=i; n=0; while(j!=0) { a[n]=j%10; j=j/10; n++; } if(n<=k) { sum=(sum+i)%1000000007;
continue; } sum1=0,sum2=0; for(t=0;t

    if(sum1==sum2)
  sum=(sum+i)%1000000007;    
}
cout<<sum;
return 0;

}

In challenges some problems marked like a unsolved, but actually it is solved, and exists accepted in submissions tab. For example, this problem :).