Function combinations_recursive

crates/openquant/src/backtesting_engine.rs:595–611

(
    start: usize,
    n: usize,
    k: usize,
    current: &mut Vec<usize>,
    out: &mut Vec<Vec<usize>>,
)

}

fn combinations_recursive(
    start: usize,
    n: usize,
    k: usize,
    current: &mut Vec<usize>,
    out: &mut Vec<Vec<usize>>,
) {
    if current.len() == k {
        out.push(current.clone());
        return;
    }
    for i in start..n {
        current.push(i);
        combinations_recursive(i + 1, n, k, current, out);
        current.pop();
    }
}

fn build_cpcv_path_assignments(
    n_groups: usize,