# Wrong answer

hi, I think my code is correct and pass all sample I/0 but when i try to submit then give me a error wrong answer

#include
using namespace std;

int main() {
int n,od=0,ev=0;
cin>>n;
for(int i=1;i<=(n*2);i++)
{
if(i>0)
{
if(i%2==0)
{
ev=ev+i;
}
else
{
od=od+i;
}
}
}
cout<<od<<" "<<ev;
return 0;
}

plzzzz help what’s problem.

Question: You are given a number N and find the sum of the first N odd and even numbers in a line separated by space. All even and odd numbers should be greater than 0.

It’s too difficult to guess the problem from code. Provide the problem link too.

1 Like

I think the problem asks to get the sum of all odd and even numbers uptil 2*n, but first of all, if you have started iterating from 1, why do you have a condition for i > 0 ??
things will be more clear when you link your submission and problem

You are given a number NN and find the sum of the first NN odd and even numbers in a line separated by space. All even and odd numbers should be greater than 00.

### Input:

• First-line will contain the number NN.

### Output:

Print the sum of the first NN odd and even numbers in a line separated by space.

### Constraints

• 1≤N≤1061≤N≤106

### Sample Input 1:

4


### Sample Output 1:

16 20


### Sample Input 2:

1


### Sample Output 2:

1 2


### EXPLANATION:

• In the first example, (1 + 3 + 5 + 7) = 16 and (2 + 4 + 6 + 8) = 20.
• In the second example, only one odd that is 1 and only one even that is 2.

1 is neither odd nor even, you are starting the for loop from 1. Maybe that is causing a problem?

really bro… but upto this what i know is that 1 is odd number. or you are saying something else.

Actually its debatable, however in programming, 1 is usually taken as an odd number.

Did you run it from two and check wether that is causing the problem?

Also, tell me what you get as a return from the compiler. A WA or a segmentation fault?

In explanation 1 take as a odd number

when i start from 2 then output is wrong

Please send me the question link.

Let’s end this discussion with my comment.

Given that N is as large as 10^6. Before getting into your solution, let’s try some examples.

N = 10
Odd = 100
Even = 110


Another example

N = 1000000
Odd = 1000000000000
Even = 1000001000000


(If you didn’t know the formula)

Odd = N * N
Even = N * (N + 1)


Now, talking about the constraints, the answer is as large as 10^{12}.
So, int, whose range is limited to about 2 \times 10^9, will not be sufficient to store this big value.

Hence, you have to use a bigger data type (usually long or long long).

In case you haven’t followed the entire explanation, here’s the code for you.

Your code, modified
#include <bits/stdc++.h>
using namespace std;

int main() {
int n = 0;
cin >> n;
long long int odd_sum = 0, even_sum = 0;
for(int i = 1; i <= 2 * n; i++) {
if(i % 2 == 0) {
even_sum += i;
}
else {
odd_sum += i;
}
}
cout << odd_sum << " " << even_sum << '\n';
return 0;
}

Usual style others prefer
#include <bits/stdc++.h>
using namespace std;

int main() {
long long int n = 0;
cin >> n;

long long int odd_sum = 0, even_sum = 0;

odd_sum = n * n;
even_sum = n * (n + 1);

cout << odd_sum << " " << even_sum << '\n';
return 0;
}

1 Like

Thanku so much that’s a right way.