Implement (partial) BST
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[package]
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name = "rust-commons"
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version = "0.1.0"
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edition = "2021"
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# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
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[dependencies]
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use std::cmp::Ordering;
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use std::collections::VecDeque;
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type Child<T> = Option<Box<Node<T>>>;
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pub struct IntoPreOrderIter<T>(T);
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pub struct IntoInOrderIter<T>(T);
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pub struct IntoPostOrderIter<T>(T);
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#[derive(Debug)]
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pub struct BST<T: Ord> {
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root: Child<T>,
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}
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#[derive(Debug)]
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struct Node<T: Ord> {
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value: T,
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left: Child<T>,
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right: Child<T>,
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}
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impl<T: Ord> Node<T> {
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fn new(value: T) -> Node<T> {
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Node {
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value,
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left: None,
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right: None,
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}
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}
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fn insert(&mut self, value: T) {
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match value.cmp(&self.value) {
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Ordering::Equal => {}
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Ordering::Less => match self.left {
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None => self.left = Some(Box::from(Node::new(value))),
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Some(ref mut node) => node.insert(value),
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},
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Ordering::Greater => match self.right {
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None => self.right = Some(Box::from(Node::new(value))),
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Some(ref mut node) => node.insert(value),
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},
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}
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}
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fn has_element(&self, value: T) -> bool {
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match value.cmp(&self.value) {
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Ordering::Equal => true,
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Ordering::Less => match self.left {
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None => false,
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Some(ref node) => node.has_element(value),
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},
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Ordering::Greater => match self.right {
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None => false,
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Some(ref node) => node.has_element(value),
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},
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}
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}
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fn retrieve(&self, value: T) -> Option<&T> {
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match value.cmp(&self.value) {
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Ordering::Equal => Some(&self.value),
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Ordering::Less => match self.left {
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None => None,
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Some(ref node) => node.retrieve(value),
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},
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Ordering::Greater => match self.right {
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None => None,
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Some(ref node) => node.retrieve(value),
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},
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}
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}
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fn retrieve_as_mut(&mut self, value: T) -> Option<&mut T> {
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match value.cmp(&self.value) {
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Ordering::Equal => Some(&mut self.value),
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Ordering::Less => match self.left {
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None => None,
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Some(ref mut node) => node.retrieve_as_mut(value),
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},
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Ordering::Greater => match self.right {
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None => None,
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Some(ref mut node) => node.retrieve_as_mut(value),
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},
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}
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}
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fn pre_order_traversal(node: Child<T>, pre_order: &mut VecDeque<T>) {
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if let Some(node) = node {
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pre_order.push_front(node.value);
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Self::pre_order_traversal(node.left, pre_order);
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Self::pre_order_traversal(node.right, pre_order);
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}
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}
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fn in_order_traversal(node: Child<T>, in_order: &mut VecDeque<T>) {
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if let Some(node) = node {
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Self::in_order_traversal(node.left, in_order);
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in_order.push_front(node.value);
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Self::in_order_traversal(node.right, in_order);
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}
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}
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fn post_order_traversal(node: Child<T>, post_order: &mut VecDeque<T>) {
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if let Some(node) = node {
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Self::post_order_traversal(node.left, post_order);
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Self::post_order_traversal(node.right, post_order);
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post_order.push_front(node.value);
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}
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}
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}
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impl<T: Ord> BST<T> {
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pub fn empty() -> Self {
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Self { root: None }
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}
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pub fn new(value: T) -> Self {
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Self {
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root: Some(Box::from(Node::new(value))),
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}
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}
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pub fn insert(&mut self, value: T) {
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match self.root {
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None => self.root = Some(Box::from(Node::new(value))),
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Some(ref mut node) => node.insert(value),
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}
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}
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pub fn has_element(&self, value: T) -> bool {
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match self.root {
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None => false,
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Some(ref node) => node.has_element(value),
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}
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}
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pub fn retrieve(&self, value: T) -> Option<&T> {
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match self.root {
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None => None,
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Some(ref node) => node.retrieve(value),
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}
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}
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pub fn retrieve_as_mut(&mut self, value: T) -> Option<&mut T> {
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match self.root {
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None => None,
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Some(ref mut node) => node.retrieve_as_mut(value),
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}
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}
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pub fn into_pre_order_iter(self) -> IntoPreOrderIter<VecDeque<T>> {
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let mut pre_order = VecDeque::new();
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Node::pre_order_traversal(self.root, &mut pre_order);
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IntoPreOrderIter(pre_order)
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}
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pub fn into_in_order_iter(self) -> IntoInOrderIter<VecDeque<T>> {
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let mut in_order = VecDeque::new();
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Node::in_order_traversal(self.root, &mut in_order);
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IntoInOrderIter(in_order)
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}
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pub fn into_post_order_iter(self) -> IntoPostOrderIter<VecDeque<T>> {
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let mut post_order = VecDeque::new();
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Node::post_order_traversal(self.root, &mut post_order);
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IntoPostOrderIter(post_order)
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}
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}
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impl<T: Ord> Iterator for IntoPreOrderIter<VecDeque<T>> {
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type Item = T;
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fn next(&mut self) -> Option<Self::Item> {
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self.0.pop_back()
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}
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}
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impl<T: Ord> Iterator for IntoInOrderIter<VecDeque<T>> {
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type Item = T;
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fn next(&mut self) -> Option<Self::Item> {
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self.0.pop_back()
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}
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}
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impl<T: Ord> Iterator for IntoPostOrderIter<VecDeque<T>> {
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type Item = T;
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fn next(&mut self) -> Option<Self::Item> {
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self.0.pop_back()
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}
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}
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// impl<T: Ord> Drop for BST<T> {
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// fn drop(&mut self) {
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// todo!("I need help with this :sob: :sob:")
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//
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// // let mut stack = vec![&self.root];
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// // let mut out: Vec<&LinkNode<T>> = Vec::new();
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// //
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// // while !stack.is_empty() {
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// // let cur_node = stack.pop().unwrap();
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// // out.push(cur_node);
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// //
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// // if let Some(node) = &cur_node.as_ref().unwrap().left {
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// // stack.push()
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// // }
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// // }
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// }
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// }
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#[cfg(test)]
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mod bst_test {
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use super::BST;
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#[test]
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fn can_insert_element() {
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let mut bst = BST::new(-1);
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bst.insert(0);
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bst.insert(1);
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bst.insert(1);
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bst.insert(2);
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assert_eq!(bst.retrieve(-1), Some(&-1));
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assert_eq!(bst.retrieve(0), Some(&0));
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assert_eq!(bst.retrieve(1), Some(&1));
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assert_eq!(bst.retrieve(2), Some(&2));
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}
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#[test]
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fn check_element_exists() {
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let mut bst = BST::empty();
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bst.insert(1);
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bst.insert(5);
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assert!(bst.has_element(1));
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assert!(bst.has_element(5));
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assert!(!bst.has_element(10));
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}
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#[test]
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fn retrieve_element_from_bst() {
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let mut bst = BST::empty();
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bst.insert(5);
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bst.insert(10);
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let retrieved_value = bst.retrieve(5);
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let invalid_value = bst.retrieve(15);
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assert_eq!(retrieved_value, Some(&5));
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assert_eq!(invalid_value, None);
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}
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#[test]
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fn retrieve_element_as_mut_and_modify_bst() {
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let mut bst = BST::empty();
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bst.insert(10);
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bst.insert(5);
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let _retrieved_value_as_mut: &mut i32 = bst.retrieve_as_mut(5).unwrap();
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*_retrieved_value_as_mut = 2;
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assert!(bst.has_element(10));
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assert!(bst.has_element(2));
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assert!(!bst.has_element(5));
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}
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#[test]
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fn pre_order_traversal() {
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let mut bst = BST::empty();
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bst.insert(3);
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bst.insert(4);
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bst.insert(5);
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bst.insert(1);
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bst.insert(2);
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let mut pre_order_iter = bst.into_pre_order_iter();
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assert_eq!(pre_order_iter.next(), Some(3));
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assert_eq!(pre_order_iter.next(), Some(1));
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assert_eq!(pre_order_iter.next(), Some(2));
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assert_eq!(pre_order_iter.next(), Some(4));
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assert_eq!(pre_order_iter.next(), Some(5));
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assert_eq!(pre_order_iter.next(), None);
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}
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#[test]
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fn in_order_traversal() {
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let mut bst = BST::empty();
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bst.insert(3);
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bst.insert(4);
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bst.insert(5);
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bst.insert(1);
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bst.insert(2);
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let mut in_order_iter = bst.into_in_order_iter();
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assert_eq!(in_order_iter.next(), Some(1));
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assert_eq!(in_order_iter.next(), Some(2));
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assert_eq!(in_order_iter.next(), Some(3));
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assert_eq!(in_order_iter.next(), Some(4));
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assert_eq!(in_order_iter.next(), Some(5));
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assert_eq!(in_order_iter.next(), None);
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}
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#[test]
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fn post_order_traversal() {
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let mut bst = BST::empty();
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bst.insert(3);
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bst.insert(4);
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bst.insert(5);
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bst.insert(1);
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bst.insert(2);
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let mut post_order_traversal = bst.into_post_order_iter();
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assert_eq!(post_order_traversal.next(), Some(2));
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assert_eq!(post_order_traversal.next(), Some(1));
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assert_eq!(post_order_traversal.next(), Some(5));
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assert_eq!(post_order_traversal.next(), Some(4));
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assert_eq!(post_order_traversal.next(), Some(3));
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assert_eq!(post_order_traversal.next(), None);
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}
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}
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@ -0,0 +1 @@
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pub mod ds;
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