-
Notifications
You must be signed in to change notification settings - Fork 19
/
mergesort.rs
56 lines (53 loc) · 1.56 KB
/
mergesort.rs
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
#![allow(clippy::many_single_char_names,clippy::explicit_counter_loop, clippy::if_same_then_else)]
pub fn mergesort<T: PartialOrd + Clone>(a: &mut [T]) {
let mut w = a.to_vec();
if a.len() > 1 {
let mid = a.len() / 2;
let (a0, a1) = a.split_at_mut(mid);
mergesort(a0);
mergesort(a1);
merge(a0, a1, &mut w);
}
a.clone_from_slice(&w);
}
fn merge<T: PartialOrd + Clone>(a0: &mut [T], a1: &mut [T], a: &mut [T]) {
let mut i0 = 0;
let mut i1 = 0;
for ai in a.iter_mut() {
if i0 == a0.len() {
*ai = a1[i1].clone();
i1 += 1;
} else if i1 == a1.len() {
*ai = a0[i0].clone();
i0 += 1;
} else if a0[i0] < a1[i1] {
*ai = a0[i0].clone();
i0 += 1;
} else {
*ai = a1[i1].clone();
i1 += 1;
}
}
}
#[cfg(test)]
mod test {
use super::mergesort;
use rand::distributions::Standard;
use rand::{thread_rng, Rng};
#[test]
fn test_mergesort() {
let mut a = [13, 8, 5, 2, 4, 0, 6, 9, 7, 3, 12, 1, 10, 11];
mergesort(&mut a);
assert_eq!(&a, &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13]);
//println!("{:?}", a);
let mut rng = thread_rng();
for _ in 0u32..50000u32 {
let len: usize = rng.gen();
let mut v: Vec<isize> = rng.sample_iter(&Standard).take((len % 32) + 1).collect();
mergesort(&mut v);
for i in 0..v.len() - 1 {
assert!(v[i] <= v[i + 1])
}
}
}
}