cargo fmt rust code (#1131)

* cargo fmt code

* Add empty line to seperate unrelated comments

* Fix review

* Update bubble_sort.rs

* Update merge_sort.rs

---------

Co-authored-by: Yudong Jin <krahets@163.com>

codes/rust/chapter_computational_complexity/space_complexity.rs

@@ -6,14 +6,14 @@
 
 include!("../include/include.rs");
 
+use list_node::ListNode;
+use std::cell::RefCell;
 use std::collections::HashMap;
 use std::rc::Rc;
-use std::cell::RefCell;
-use list_node::ListNode;
 use tree_node::TreeNode;
 
 /* 函数 */
-fn function() ->i32 {
+fn function() -> i32 {
     // 执行某些操作
     return 0;
 }
@@ -56,7 +56,9 @@ fn linear(n: i32) {
 /* 线性阶（递归实现） */
 fn linear_recur(n: i32) {
     println!("递归 n = {}", n);
-    if n == 1 {return};
+    if n == 1 {
+        return;
+    };
     linear_recur(n - 1);
 }
 
@@ -78,7 +80,9 @@ fn quadratic(n: i32) {
 
 /* 平方阶（递归实现） */
 fn quadratic_recur(n: i32) -> i32 {
-    if n <= 0 {return 0};
+    if n <= 0 {
+        return 0;
+    };
     // 数组 nums 长度为 n, n-1, ..., 2, 1
     let nums = vec![0; n as usize];
     println!("递归 n = {} 中的 nums 长度 = {}", n, nums.len());
@@ -87,7 +91,9 @@ fn quadratic_recur(n: i32) -> i32 {
 
 /* 指数阶（建立满二叉树） */
 fn build_tree(n: i32) -> Option<Rc<RefCell<TreeNode>>> {
-    if n == 0 {return None};
+    if n == 0 {
+        return None;
+    };
     let root = TreeNode::new(0);
     root.borrow_mut().left = build_tree(n - 1);
     root.borrow_mut().right = build_tree(n - 1);
@@ -107,5 +113,5 @@ fn main() {
     quadratic_recur(n);
     // 指数阶
     let root = build_tree(n);
-    print_util::print_tree(&root.unwrap());   
-}
+    print_util::print_tree(&root.unwrap());
+}