sort-steps 0.2.4

use std::cmp::Ordering;

/// Sorts a slice of data using the stooge sort algorithm with a custom comparator.
///
/// # Examples
///
/// ```
/// # use sort_steps::{heap_sort_by, stooge_sort};
/// let numbers = [5, 9, 3, 6, 8, 2, 1, 7, 4];
/// println!("Heap Sort Steps:");
/// for (i, v) in stooge_sort(&numbers).enumerate() {
///     println!("#{:02}: {:?}", i, v);
/// }
/// ```
pub fn stooge_sort<T>(v: &[T]) -> impl Iterator<Item = Vec<T>>
where
    T: PartialOrd + Clone,
{
    stooge_sort_by(v, |a, b| a.partial_cmp(b))
}

/// Sorts a slice of data using the stooge sort algorithm with a custom comparator.
///
/// # Examples
///
/// ```
/// # use sort_steps::{stooge_sort_by};
/// let numbers = [5, 9, 3, 6, 8, 2, 1, 7, 4];
/// println!("Heap Sort Steps:");
/// for (i, v) in stooge_sort_by(&numbers, |a, b| a.partial_cmp(b)).enumerate() {
///     println!("#{:02}: {:?}", i, v);
/// }
/// ```
pub fn stooge_sort_by<T, F>(v: &[T], compare: F) -> impl Iterator<Item = Vec<T>>
where
    F: Fn(&T, &T) -> Option<Ordering> + Copy,
    T: Clone,
{
    let mut result = Vec::new();
    let mut v_clone = v.to_vec();
    stooge_sort_helper(&mut v_clone, compare, &mut result);
    result.into_iter()
}

// Helper function to perform stooge sort and collect steps
fn stooge_sort_helper<T, F>(v: &mut [T], compare: F, steps: &mut Vec<Vec<T>>)
where
    F: Fn(&T, &T) -> Option<Ordering> + Copy,
    T: Clone,
{
    let n = v.len();
    if n <= 1 {
        return;
    }

    if let Some(Ordering::Greater) = compare(&v[0], &v[n - 1]) {
        v.swap(0, n - 1);
        steps.push(v.to_vec());
    }

    if n > 2 {
        let third = n / 3;
        stooge_sort_helper(&mut v[..n - third], compare, steps);
        stooge_sort_helper(&mut v[third..], compare, steps);
        stooge_sort_helper(&mut v[..n - third], compare, steps);
    }
}