#[cfg(test)]
mod tests {
use crate::merge_sort;
#[test]
fn sort() {
let mut data = vec![5, 4, 3, 2, 1];
let result = merge_sort(&mut data);
assert_eq!(result, [1, 2, 3, 4, 5]);
}
}
pub fn merge_sort<T: PartialOrd + Clone>(v: &mut [T]) -> Vec<T> {
let l = v.len();
if l < 2 {
return v.to_vec();
}
let m = (l as f64 / 2.).floor() as usize;
let (lp, rp) = v.split_at_mut(m);
let lv = merge_sort(lp);
let rv = merge_sort(rp);
let lvl = lv.len();
let rvl = rv.len();
let mut li = 0;
let mut ri = 0;
let mut new_v = Vec::with_capacity(l);
loop {
if lv[li] > rv[ri] {
new_v.push(rv[ri].clone());
ri += 1;
} else {
new_v.push(lv[li].clone());
li += 1;
}
if li == lvl {
new_v.extend_from_slice(&rv[ri..]);
break;
}
if ri == rvl {
new_v.extend_from_slice(&lv[li..]);
break;
}
}
new_v
}