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#![cfg_attr(not(test), no_std)]
#[cfg(test)]
extern crate std as core;
use core::cmp::Ordering;
fn quicksort_helper<T, F>(arr: &mut [T], left: isize, right: isize, compare: &F)
where F: Fn(&T, &T) -> Ordering {
if right <= left {
return
}
let mut i: isize = left - 1;
let mut j: isize = right;
let mut p: isize = i;
let mut q: isize = j;
unsafe {
let v: *mut T = &mut arr[right as usize];
loop {
i += 1;
while compare(&arr[i as usize], &*v) == Ordering::Less {
i += 1
}
j -= 1;
while compare(&*v, &arr[j as usize]) == Ordering::Less {
if j == left {
break
}
j -= 1;
}
if i >= j {
break
}
arr.swap(i as usize, j as usize);
if compare(&arr[i as usize], &*v) == Ordering::Equal {
p += 1;
arr.swap(p as usize, i as usize)
}
if compare(&*v, &arr[j as usize]) == Ordering::Equal {
q -= 1;
arr.swap(j as usize, q as usize)
}
}
}
arr.swap(i as usize, right as usize);
j = i - 1;
i += 1;
let mut k: isize = left;
while k < p {
arr.swap(k as usize, j as usize);
k += 1;
j -= 1;
assert!(k < arr.len() as isize);
}
k = right - 1;
while k > q {
arr.swap(i as usize, k as usize);
k -= 1;
i += 1;
assert!(k != 0);
}
quicksort_helper(arr, left, j, compare);
quicksort_helper(arr, i, right, compare);
}
pub fn quicksort_by<T, F>(arr: &mut [T], compare: F) where F: Fn(&T, &T) -> Ordering {
if arr.len() <= 1 {
return
}
let len = arr.len();
quicksort_helper(arr, 0, (len - 1) as isize, &compare);
}
#[inline]
pub fn quicksort<T>(arr: &mut [T]) where T: Ord {
quicksort_by(arr, |a, b| a.cmp(b))
}
#[cfg(test)]
extern crate rand;
#[cfg(test)]
pub mod test {
use rand::{self, Rng};
use super::quicksort;
#[test]
pub fn random() {
let mut rng = rand::thread_rng();
for _ in 0u32 .. 50000u32 {
let len: usize = rng.gen();
let mut v: Vec<isize> = rng.gen_iter::<isize>().take((len % 32) + 1).collect();
quicksort(&mut v);
for i in 0 .. v.len() - 1 {
assert!(v[i] <= v[i + 1])
}
}
}
}