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binary_search_tree.rs
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binary_search_tree.rs
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use std::ptr::NonNull;
#[derive(Eq, PartialEq, Ord, PartialOrd, Clone, Copy)]
struct TreeNode<T> {
value: T,
left: Option<NonNull<TreeNode<T>>>,
right: Option<NonNull<TreeNode<T>>>
}
#[derive(Eq, PartialEq, Ord, PartialOrd, Clone, Copy)]
pub struct BinarySearchTree<T> {
root: Option<NonNull<TreeNode<T>>>,
pub length: u32
}
impl<T> TreeNode<T> {
fn new(value: T) -> Self {
TreeNode {
value,
left: None,
right: None
}
}
}
impl<T: Ord + PartialOrd + Copy> BinarySearchTree<T> {
pub fn new() -> Self {
BinarySearchTree {
root: None,
length: 0
}
}
pub fn insert(&mut self, value: T) {
if let Some(root) = self.root {
unsafe {
insert_value(&mut (*root.as_ptr()), value);
self.length += 1;
}
} else {
let root_box = Box::new(TreeNode::<T>::new(value));
let root_ptr = NonNull::new(Box::into_raw(root_box));
self.root = root_ptr;
self.length += 1;
}
}
pub fn delete(&mut self, value: T) {
if let Some(mut root) = self.root {
unsafe {
self.root = delete_node(&mut root, value);
self.length -= 1;
}
}
}
pub fn get_all(&self) -> Vec<T> {
let mut all = Vec::new();
if let Some(root) = self.root {
unsafe {
get_all_in_order(&root, &mut all);
}
}
all
}
pub fn clear(&mut self) {
unsafe {
if let Some(root) = self.root {
clear_all_nodes(&root);
}
}
self.root = None;
self.length = 0;
}
}
unsafe fn insert_value<T: Ord + PartialOrd>(node: &mut TreeNode<T>, value: T) {
let target_node =
if value < node.value {
&mut node.left
} else {
&mut node.right
};
match target_node {
Some(ptr) => insert_value(&mut (*ptr.as_ptr()), value),
None => {
let node_box = Box::new(TreeNode::<T>::new(value));
let node_ptr = NonNull::new(Box::into_raw(node_box));
*target_node = node_ptr;
}
}
}
unsafe fn get_all_in_order<T: Copy>(node: &NonNull<TreeNode<T>>, all: &mut Vec<T>) {
let tree_node = &(*node.as_ptr());
if let Some(left_node) = tree_node.left {
get_all_in_order(&left_node, all);
}
all.push(tree_node.value);
if let Some(right_node) = tree_node.right {
get_all_in_order(&right_node, all);
}
}
unsafe fn clear_all_nodes<T>(node: &NonNull<TreeNode<T>>) {
let boxed_node = Box::from_raw(node.as_ptr());
if let Some(left_node) = boxed_node.left {
clear_all_nodes(&left_node);
}
if let Some(right_node) = boxed_node.right {
clear_all_nodes(&right_node);
}
}
unsafe fn delete_node<T: Ord + PartialOrd + Copy>(node: &mut NonNull<TreeNode<T>>, value: T) -> Option<NonNull<TreeNode<T>>> {
let tree_node = &mut *node.as_ptr();
if value < tree_node.value {
if let Some(mut left_node) = tree_node.left {
tree_node.left = delete_node(&mut left_node, value);
}
} else if value > tree_node.value {
if let Some(mut right_node) = tree_node.right {
tree_node.right = delete_node(&mut right_node, value);
}
} else {
if tree_node.left.is_none() {
return tree_node.right;
} else if tree_node.right.is_none() {
return tree_node.left;
}
let mut successor = min_value_node(tree_node.right.unwrap());
tree_node.value = (*successor.as_ptr()).value;
tree_node.right = delete_node(&mut successor, tree_node.value);
}
Some(*node)
}
unsafe fn min_value_node<T>(node: NonNull<TreeNode<T>>) -> NonNull<TreeNode<T>> {
let mut current = node;
while let Some(left) = (*current.as_ptr()).left {
current = left;
}
current
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_insert() {
let mut bst = BinarySearchTree::new();
bst.insert(5);
bst.insert(3);
bst.insert(7);
assert_eq!(bst.length, 3);
}
#[test]
fn test_get_all() {
let mut bst = BinarySearchTree::new();
bst.insert(5);
bst.insert(3);
bst.insert(7);
assert_eq!(bst.get_all(), vec![3, 5, 7]);
}
#[test]
fn test_delete() {
let mut bst = BinarySearchTree::new();
bst.insert(5);
bst.insert(3);
bst.insert(7);
bst.delete(7);
assert_eq!(bst.get_all(), vec![3, 5]);
assert_eq!(bst.length, 2);
}
#[test]
fn test_clear() {
let mut bst = BinarySearchTree::new();
bst.insert(5);
bst.insert(3);
bst.insert(7);
bst.clear();
assert_eq!(bst.get_all(), Vec::<i32>::new());
assert_eq!(bst.length, 0);
}
}