Help me in solving RECUR05 problem

help
,
1

My issue

include

using namespace std;

int fib(int n) {
if (n <= 1) {
return n;
}

int a = 0; // Initialize first Fibonacci number (fib(0))
int b = 1; // Initialize second Fibonacci number (fib(1))
int fib_num = 0; // Variable to store nth Fibonacci number

// Calculate nth Fibonacci number iteratively
for (int i = 2; i <= n; ++i) {
    fib_num = a + b;
    a = b;
    b = fib_num;
}

return fib_num;

}

int main() {
int n;
cin >> n;
cout << fib(n) << endl;
return 0;
}
it shows hidden error give it correct.

My code

#include <iostream>

using namespace std;

int fib(int n) {
    if (n <= 1) {
        return n;
    }

    int a = 0; // Initialize first Fibonacci number (fib(0))
    int b = 1; // Initialize second Fibonacci number (fib(1))
    int fib_num = 0; // Variable to store nth Fibonacci number

    // Calculate nth Fibonacci number iteratively
    for (int i = 2; i <= n; ++i) {
        fib_num = a + b;
        a = b;
        b = fib_num;
    }

    return fib_num;
}

int main() {
    int n;
    cin >> n;
    cout << fib(n) << endl;
    return 0;
}

Learning course: Design and Analysis of Algorithms
Problem Link: Fibonacci Series in Design and Analysis of Algorithms