refactor(medium): add type tree in 102 problem

Author: bujosa

src/main.rs

@@ -1,9 +1,18 @@
 mod medium;
 
 fn main() {
-    use leetcode::medium::remove_nth_node_from_end_of_list::ListNode;
-    let head = ListNode::from_vec(vec![1, 2, 3, 4, 5]);
-    let result = leetcode::medium::remove_nth_node_from_end_of_list::remove_nth_from_end(head, 2);
+    use leetcode::medium::binary_tree_level_order_traversal::{level_order, TreeNode};
+    let root = TreeNode::from_vec(vec![
+        Some(3),
+        Some(9),
+        Some(20),
+        None,
+        None,
+        Some(15),
+        Some(7),
+    ]);
+
+    let result = level_order(root);
     println!("result: {:?}", result);
 }
 

src/medium/binary_tree_level_order_traversal.rs

@@ -2,12 +2,14 @@
 use std::cell::RefCell;
 use std::rc::Rc;
 
+type Tree = Option<Rc<RefCell<TreeNode>>>;
+
 // Definition for a binary tree node.
 #[derive(Debug, PartialEq, Eq)]
 pub struct TreeNode {
     pub val: i32,
-    pub left: Option<Rc<RefCell<TreeNode>>>,
-    pub right: Option<Rc<RefCell<TreeNode>>>,
+    pub left: Tree,
+    pub right: Tree,
 }
 
 impl TreeNode {
@@ -21,7 +23,7 @@ impl TreeNode {
     }
 
     #[inline]
-    pub fn from_vec(vec: Vec<Option<i32>>) -> Option<Rc<RefCell<TreeNode>>> {
+    pub fn from_vec(vec: Vec<Option<i32>>) -> Tree {
         let mut nodes = vec![];
 
         for val in vec {
@@ -50,7 +52,7 @@ impl TreeNode {
     }
 }
 
-pub fn level_order(root: Option<Rc<RefCell<TreeNode>>>) -> Vec<Vec<i32>> {
+pub fn level_order(root: Tree) -> Vec<Vec<i32>> {
     let mut result = vec![];
     if root.is_none() {
         return result;

src/medium/readme.md

@@ -333,16 +333,15 @@ Put the code below in main.rs and run `cargo run`
 
 ```rust
     use leetcode::medium::binary_tree_level_order_traversal::{level_order, TreeNode};
-    let mut root = TreeNode::new(3);
-    let mut node9 = TreeNode::new(9);
-    let mut node20 = TreeNode::new(20);
-    let mut node15 = TreeNode::new(15);
-    let mut node7 = TreeNode::new(7);
-
-    node20.left = Some(Rc::new(RefCell::new(node15)));
-    node20.right = Some(Rc::new(RefCell::new(node7)));
-    root.left = Some(Rc::new(RefCell::new(node9)));
-    root.right = Some(Rc::new(RefCell::new(node20)));
+    let root = TreeNode::from_vec(vec![
+            Some(3),
+            Some(9),
+            Some(20),
+            None,
+            None,
+            Some(15),
+            Some(7),
+    ]);
 
     let result = level_order(root);
     println!("result: {:?}", result);