二叉搜尋樹 Rust實現

摘要： 二叉搜尋樹 二叉搜尋樹是一顆二叉樹 每個節點應該包含三個屬性left ,right ,p , 根節點p 為NIL 設x是二叉搜尋樹的一個節點, y是x左子樹的一個節點, 那麼y....

二叉搜尋樹

• 二叉搜尋樹是一顆二叉樹
• 每個節點應該包含三個屬性left ,right ,p , 根節點p 為NIL
• 設x是二叉搜尋樹的一個節點, y是x左子樹的一個節點, 那麼y.key <= x.key , 若y是x右子樹的一個節點, 那麼y.key >= x.key

遍歷

遍歷分前中後, 以根節點的遍歷順序而劃分

之前寫過一篇二叉搜尋樹的, 用C語言實現, 可以參考一下C語言實現

感受一下區別

以下是程式碼, 來源於ofollow,noindex" target="_blank">RustPrimer

type TreeNode<K, V> = Option<Box<Node<K, V>>>;
#[derive(Debug)]
struct Node<K, V: std::fmt::Display> {
left: TreeNode<K, V>,
right: TreeNode<K, V>,
key: K,
value: V,
}
trait BinaryTree<K, V> {
fn pre_order(&self);
fn in_order(&self);
fn pos_order(&self);
}
trait BinarySearchTree<K: PartialOrd, V>: BinaryTree<K, V> {
fn insert(&mut self, key: K, value: V);
}
impl<K, V: std::fmt::Display> Node<K, V> {
fn new(key: K, value: V) -> Self {
Node {
left: None,
right: None,
value: value,
key: key,
}
}
}
impl<K: PartialOrd, V: std::fmt::Display> BinarySearchTree<K, V> for Node<K, V> {
fn insert(&mut self, key: K, value: V) {
if self.key < key {
if let Some(ref mut right) = self.right {
right.insert(key, value);
} else {
self.right = Some(Box::new(Node::new(key, value)));
}
} else {
if let Some(ref mut left) = self.left {
left.insert(key, value);
} else {
self.left = Some(Box::new(Node::new(key, value)));
}
}
}
}
impl<K, V: std::fmt::Display> BinaryTree<K, V> for Node<K, V> {
fn pre_order(&self) {
println!("{}", self.value);

if let Some(ref left) = self.left {
left.pre_order();
}
if let Some(ref right) = self.right {
right.pre_order();
}
}

fn in_order(&self) {
if let Some(ref left) = self.left {
left.in_order();
}
println!("{}", self.value);
if let Some(ref right) = self.right {
right.in_order();
}
}
fn pos_order(&self) {
if let Some(ref left) = self.left {
left.pos_order();
}
if let Some(ref right) = self.right {
right.pos_order();
}
println!("{}", self.value);
}
}

type BST<K, V> = Node<K, V>;

fn test_insert() {
let mut root = BST::<i32, i32>::new(3, 4);
root.insert(2, 3);
root.insert(4, 6);
root.insert(5, 5);
root.insert(6, 6);
root.insert(1, 8);
if let Some(ref left) = root.left {
assert_eq!(left.value, 3);
}

if let Some(ref right) = root.right {
assert_eq!(right.value, 6);
if let Some(ref right) = right.right {
assert_eq!(right.value, 5);
}
}
println!("Pre Order traversal");
root.pre_order();
println!("In Order traversal");
root.in_order();
println!("Pos Order traversal");
root.pos_order();
}

fn main() {
test_insert();
}