Fix rust compile warning and an obvious print error in array.rs (#1144)

* Fix rust compile warning and an obvious print error in array.rs

* Update LinkedList

1. drop unnessaray mut borrow
2. fmt code and make variable more readable

* follow convention of this repo

* Update list_node.rs

---------

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

codes/rust/chapter_array_and_linkedlist/array.rs

@@ -90,7 +90,7 @@ fn main() {
     // 长度扩展
     let mut nums = extend(nums, 3);
     print!("将数组长度扩展至 8 ，得到 nums = ");
-    print_util::print_array(&arr);
+    print_util::print_array(&nums);
 
     // 插入元素
     insert(&mut nums, 6, 3);

codes/rust/chapter_array_and_linkedlist/linked_list.rs

@@ -37,9 +37,10 @@ pub fn access<T>(head: Rc<RefCell<ListNode<T>>>, index: i32) -> Rc<RefCell<ListN
     if index <= 0 {
         return head;
     };
-    if let Some(node) = &head.borrow_mut().next {
+    if let Some(node) = &head.borrow().next {
         return access(node.clone(), index - 1);
     }
+
     return head;
 }
 

codes/rust/chapter_sorting/quick_sort.rs

@@ -45,11 +45,11 @@ struct QuickSortMedian;
 impl QuickSortMedian {
     /* 选取三个候选元素的中位数 */
     fn median_three(nums: &mut [i32], left: usize, mid: usize, right: usize) -> usize {
-        let (mut l, mut m, mut r) = (nums[left], nums[mid], nums[right]);
+        let (l, m, r) = (nums[left], nums[mid], nums[right]);
-        if ((l <= m && m <= r) || (r <= m && m <= l)) {
+        if (l <= m && m <= r) || (r <= m && m <= l) {
             return mid; // m 在 l 和 r 之间
         }
-        if ((m <= l && l <= r) || (r <= l && l <= m)) {
+        if (m <= l && l <= r) || (r <= l && l <= m) {
             return left; // l 在 m 和 r 之间
         }
         right

codes/rust/include/list_node.rs

@@ -1,12 +1,12 @@
 /*
  * File: list_node.rs
  * Created Time: 2023-03-05
- * Author: codingonion (coderonion@gmail.com)
+ * Author: codingonion (coderonion@gmail.com), rongyi (hiarongyi@gmail.com)
  */
 
-use std::rc::Rc;
 use std::cell::RefCell;
 use std::collections::HashMap;
+use std::rc::Rc;
 
 #[derive(Debug)]
 pub struct ListNode<T> {
@@ -16,25 +16,21 @@ pub struct ListNode<T> {
 
 impl<T> ListNode<T> {
     pub fn new(val: T) -> Rc<RefCell<ListNode<T>>> {
-        Rc::new(RefCell::new(ListNode {
+        Rc::new(RefCell::new(ListNode { val, next: None }))
-            val,
-            next: None,
-        }))
     }
-    
+
     /* Generate a linked list with an array */
-    pub fn arr_to_linked_list(array: &[T]) -> Option<Rc<RefCell<ListNode<T>>>> 
+    pub fn arr_to_linked_list(array: &[T]) -> Option<Rc<RefCell<ListNode<T>>>>
     where
         T: Copy + Clone,
     {
         let mut head = None;
-        let mut prev = None;
+        // insert in reverse order
         for item in array.iter().rev() {
             let node = Rc::new(RefCell::new(ListNode {
                 val: *item,
-                next: prev.take(),
+                next: head.clone(),
             }));
-            prev = Some(node.clone());
             head = Some(node);
         }
         head
@@ -43,9 +39,9 @@ impl<T> ListNode<T> {
     /* Generate a hashmap with a linked_list */
     pub fn linked_list_to_hashmap(
         linked_list: Option<Rc<RefCell<ListNode<T>>>>,
-    ) -> HashMap<T, Rc<RefCell<ListNode<T>>>> 
+    ) -> HashMap<T, Rc<RefCell<ListNode<T>>>>
     where
-        T: std::hash::Hash + Eq + Copy + Clone
+        T: std::hash::Hash + Eq + Copy + Clone,
     {
         let mut hashmap = HashMap::new();
         if let Some(node) = linked_list {