CoPilot does it right for Python but not C++

Here is the problem I wanted CoPilot to solve:

Represent a positive number as a sum of fibonacci numbers.

Python Solution

def fibsum (n):
    """
    Return a list of fibonacci numbers that sum to n.
    """
    fib = [1, 1]
    while fib[-1] < n:
        fib.append(fib[-1] + fib[-2])
    fib.reverse()
    result = []
    for f in fib:
        if n >= f:
            result.append(f)
            n -= f
    return result

The C++ code is obviously wrong:

/*
Represent a positive number as a sum of fibonacci numbers.
*/
vector<int> fibSum(int n) {
    vector<int> fibs;
    int a = 1, b = 1;
    while (n > 0) {
        if (n >= b) {
            fibs.push_back(b);
            n -= b;
        }
        int c = a + b;
        a = b;
        b = c;
    }
    return fibs;
}