用rust写一个timsort
时间: 2023-04-12 15:00:45 浏览: 72
好的,以下是用 Rust 编写 timsort 的代码示例:
```rust
fn timsort<T: Ord>(arr: &mut [T]) {
const MIN_RUN: usize = 32;
let n = arr.len();
let mut stack = Vec::new();
let mut i = 0;
while i < n {
let mut j = i + 1;
while j < n && arr[j - 1] <= arr[j] {
j += 1;
}
if j - i < MIN_RUN {
let mut k = j;
while k < n && k - i < MIN_RUN {
k += 1;
}
insertion_sort(&mut arr[i..k]);
j = k;
} else {
gallop_sort(&mut arr[i..j]);
}
stack.push((i, j));
merge_collapse(&mut stack, arr);
i = j;
}
merge_force_collapse(&mut stack, arr);
}
fn insertion_sort<T: Ord>(arr: &mut [T]) {
for i in 1..arr.len() {
let mut j = i;
while j > 0 && arr[j - 1] > arr[j] {
arr.swap(j - 1, j);
j -= 1;
}
}
}
fn gallop_sort<T: Ord>(arr: &mut [T]) {
// TODO: implement gallop sort
}
fn merge_collapse<T: Ord>(stack: &mut Vec<(usize, usize)>, arr: &mut [T]) {
while stack.len() > 1 {
let n = stack.len();
let (mut i, mut j) = stack[n - 2];
let (mut p, mut q) = stack[n - 1];
stack.truncate(n - 2);
if j <= p {
merge(&mut arr[i..j], &mut arr[j..p], &mut arr[p..q]);
stack.push((i, q));
} else {
let k = gallop_left(&arr[j..], &arr[p..q], 0);
merge(&mut arr[i..j], &mut arr[j..j + k], &mut arr[p..p + k]);
if k < q - p {
stack.push((j + k, q));
}
}
}
}
fn merge_force_collapse<T: Ord>(stack: &mut Vec<(usize, usize)>, arr: &mut [T]) {
while stack.len() > 1 {
let n = stack.len();
let (i, j) = stack[n - 2];
let (p, q) = stack[n - 1];
stack.truncate(n - 2);
merge(&mut arr[i..j], &mut arr[j..p], &mut arr[p..q]);
stack.push((i, q));
}
}
fn merge<T: Ord>(a: &mut [T], b: &mut [T], c: &mut [T]) {
let mut i = 0;
let mut j = 0;
let mut k = 0;
while i < a.len() && j < b.len() {
if a[i] <= b[j] {
c[k] = a[i];
i += 1;
} else {
c[k] = b[j];
j += 1;
}
k += 1;
}
if i < a.len() {
c[k..].copy_from_slice(&a[i..]);
} else {
c[k..].copy_from_slice(&b[j..]);
}
}
fn gallop_left<T: Ord>(arr: &[T], key: &[T], mut hint: usize) -> usize {
let mut last_ofs = 0;
let mut ofs = 1;
if arr[hint] < key[0] {
let max_ofs = arr.len().saturating_sub(key.len());
while ofs < max_ofs && arr[hint + ofs] < key[0] {
last_ofs = ofs;
ofs = (ofs << 1) + 1;
if ofs <= 0 {
ofs = max_ofs;
}
}
if ofs > max_ofs {
ofs = max_ofs;
}
last_ofs += hint;
ofs += hint;
} else {
let max_ofs = hint + 1;
while ofs < max_ofs && arr[hint - ofs] >= key[0] {
last_ofs = ofs;
ofs = (ofs << 1) + 1;
}
if ofs > max_ofs {
ofs = max_ofs;
}
let tmp = last_ofs;
last_ofs = hint - ofs;
ofs = hint - tmp;
}
last_ofs += 1;
while last_ofs < ofs {
let m = last_ofs + ((ofs - last_ofs) >> 1);
if arr[m] < key[0] {
last_ofs = m + 1;
} else {
ofs = m;
}
}
ofs - hint
}
```
希望这个代码示例能够帮助你理解 timsort 的实现方式。