zig : update codes style && rust : add codes for chapter_backtracking. (#613)

* zig : update codes style

* rust : add codes for chapter_backtracking

* zig : update codes style

codes/rust/chapter_backtracking/preorder_traversal_i_compact.rs

@@ -0,0 +1,43 @@
+/*
+ * File: preorder_traversal_i_compact.rs
+ * Created Time: 2023-07-15
+ * Author: sjinzh (sjinzh@gmail.com)
+ */
+
+ include!("../include/include.rs");
+
+use std::{cell::RefCell, rc::Rc};
+use tree_node::{vec_to_tree, TreeNode};
+
+/* 前序遍历：例题一 */
+fn pre_order(res: &mut Vec<Rc<RefCell<TreeNode>>>, root: Option<Rc<RefCell<TreeNode>>>) {
+    if root.is_none() {
+        return;
+    }
+    if let Some(node) = root {
+        if node.borrow().val == 7 {
+            // 记录解
+            res.push(node.clone());
+        }
+        pre_order(res, node.borrow().left.clone());
+        pre_order(res, node.borrow().right.clone());
+    }
+}
+
+/* Driver Code */
+pub fn main() {
+    let root = vec_to_tree([1, 7, 3, 4, 5, 6, 7].map(|x| Some(x)).to_vec());
+    println!("初始化二叉树");
+    print_util::print_tree(root.as_ref().unwrap());
+
+    // 前序遍历
+    let mut res = Vec::new();
+    pre_order(&mut res, root);
+
+    println!("\n输出所有值为 7 的节点");
+    let mut vals = Vec::new();
+    for node in res {
+        vals.push(node.borrow().val)
+    }
+    println!("{:?}", vals);
+}