FLOW004 solution not being accepted

[jain2004vedika]

Problem: FLOW004 Problem - CodeChef

The code below runs successfully, gives correct output with custom input. But upon submission, the answer is marked wrong. Can someone help me out with it?

#include
using namespace std;

int main() {
int a, b;
cin>>a;
if (a>=1 && a<=1000){
for (int c=0;c<a;c++){
cin>>b;
if (b>=1 && b<=1000000){
int d=0;
if (b>=10){
d=b%10;
while (b>=10){
b/=10;
}
}
d+=b;
cout<<d<<endl;
}
}
}
return 0;
}

[ayushkr07]

Please go through this answer, it should resolve the issue:

It gives correct submission for wrong code.WHY??

Hi, in the question it is mentioned to find sum of first and last digit of given integer so, if we are given a single-digit integer the number itself is first and last number. If input is 1, then output should be 1+1=2. The second code mentioned above doesn’t work because of this if condition here: if(n>=10){ int a=n%10; while(n>=10){ n=n/10; } If the number is less than 10 then int a never gets declared and no value is then added in this operation int k=a+n; so k here simply equals to n.

[srikarsam4]

take all your int as long long int. also why can’t you add the first digit (sum+=a%10)take a single while loop until a>=10 where a=a/10 and then add the last digit. (sum+=a) and print it

[jain2004vedika]

Can you look into my code specifically and then point out the error? The person whom you replied to in that answer has a different code. Moreover, as far as I understood the problem, the output for a single digit input should be the single digit itself, not its double. Even when I gave the latter as the output for a sigle digit input, my answer had been marked wrong.

[jain2004vedika]

a is the counter for the no. of test cases. b is the particular test case. What you suggested is exactly what I did in my code. The answer is marked wrong.

[ayushkr07]

@jain2004vedika

Moreover, as far as I understood the problem, the output for a single digit input should be the single digit itself, not its double.

When the input is a single-digit number then the number itself is the first digit and the last digit, so we are not just doubling it, we are adding it twice.

@jain2004vedika

if (b>=10){
d=b%10;
while (b>=10){
b/=10;
}
}

Now in the above part of your code, due to this condition:

if (b>=10)

value of d in d=b%10; is never assigned for a single-digit input and it remains 0.

Later when you add d+=b; as d value is zero and b value is the input, so d values becomes the same as the input.

So, for a single-digit value, you will print the digit itself instead of its double.

How to resolve this issue??
Remove this condition, that’s it:

if (b>=10)

[jain2004vedika]

The problem was with my logic. Single digit had to be indeed added twice. Answer accepted.

The working code:

#include
using namespace std;

int main() {
int a, b;
cin>>a;
if (a>=1 && a<=1000){
for (int c=0;c<a;c++){
cin>>b;
if (b>=1 && b<=1000000){
int d=0;
d=b%10;
if (b>=10){
while (b>=10){
b/=10;
}
}
d+=b;
cout<<d<<endl;
}
}
}
return 0;
}