✨ feat(rust/tree): add binary_tree_bfs, binary_tree_dfs, (#450)

* ✨ feat(rust/tree): add binary_tree_dfs

* ✨ feat(rust/tree): add binary_tree_bfs

* 🐞 fix(rust/tree): can't list to any kind of tree

codes/rust/chapter_tree/binary_tree_bfs.rs

@@ -0,0 +1,42 @@
+/**
+ * File: binary_tree_bfs.rs
+ * Created Time: 2023-04-07
+ * Author: xBLACKICEx (xBLACKICE@outlook.com)
+ */
+
+use std::collections::VecDeque;
+use std::{cell::RefCell, rc::Rc};
+use tree_node::{vec_to_tree, TreeNode};
+include!("../include/include.rs");
+
+fn level_order(root: &Rc<RefCell<TreeNode>>) -> Vec<i32> {
+    // 初始化队列，加入根结点
+    let mut que = VecDeque::new();
+    que.push_back(Rc::clone(&root));
+    // 初始化一个列表，用于保存遍历序列
+    let mut vec = Vec::new();
+
+    while let Some(node) = que.pop_front() {                // 队列出队
+        vec.push(node.borrow().val);                        // 保存结点值
+        if let Some(left) = node.borrow().left.as_ref() {
+            que.push_back(Rc::clone(left));                 // 左子结点入队
+        }
+        if let Some(right) = node.borrow().right.as_ref() {
+            que.push_back(Rc::clone(right));                // 右子结点入队
+        };
+    }
+    vec
+}
+
+/* Driver Code */
+fn main() {
+    /* 初始化二叉树 */
+    // 这里借助了一个从数组直接生成二叉树的函数
+    let root = vec_to_tree(op_vec![1, 2, 3, 4, 5, 6, 7]).unwrap();
+    println!("初始化二叉树\n");
+    print_util::print_tree(&root);
+
+    /* 层序遍历 */
+    let vec = level_order(&root);
+    print!("\n层序遍历的结点打印序列 = {:?}", vec);
+}