Idiomatic rust (#1505)

Author: rongyi

codes/rust/include/list_node.rs

@@ -29,7 +29,7 @@ impl<T> ListNode<T> {
         for item in array.iter().rev() {
             let node = Rc::new(RefCell::new(ListNode {
                 val: *item,
-                next: head.clone(),
+                next: head.take(),
             }));
             head = Some(node);
         }
@@ -44,14 +44,14 @@ impl<T> ListNode<T> {
         T: std::hash::Hash + Eq + Copy + Clone,
     {
         let mut hashmap = HashMap::new();
-        if let Some(node) = linked_list {
-            let mut current = Some(node.clone());
-            while let Some(cur) = current {
-                let borrow = cur.borrow();
-                hashmap.insert(borrow.val.clone(), cur.clone());
-                current = borrow.next.clone();
-            }
+        let mut node = linked_list;
+
+        while let Some(cur) = node {
+            let borrow = cur.borrow();
+            hashmap.insert(borrow.val.clone(), cur.clone());
+            node = borrow.next.clone();
         }
+
         hashmap
     }
 }

codes/rust/include/tree_node.rs

@@ -72,23 +72,21 @@ pub fn vec_to_tree(arr: Vec<Option<i32>>) -> Option<Rc<RefCell<TreeNode>>> {
 }
 
 /* 将二叉树序列化为列表：递归 */
-fn tree_to_vec_dfs(root: Option<Rc<RefCell<TreeNode>>>, i: usize, res: &mut Vec<Option<i32>>) {
-    if root.is_none() {
-        return;
+fn tree_to_vec_dfs(root: Option<&Rc<RefCell<TreeNode>>>, i: usize, res: &mut Vec<Option<i32>>) {
+    if let Some(root) = root {
+        // i + 1 is the minimum valid size to access index i
+        while res.len() < i + 1 {
+            res.push(None);
+        }
+        res[i] = Some(root.borrow().val);
+        tree_to_vec_dfs(root.borrow().left.as_ref(), 2 * i + 1, res);
+        tree_to_vec_dfs(root.borrow().right.as_ref(), 2 * i + 2, res);
     }
-    let root = root.unwrap();
-    // i + 1 is the minimum valid size to access index i
-    while res.len() < i + 1 {
-        res.push(None);
-    }
-    res[i] = Some(root.borrow().val);
-    tree_to_vec_dfs(root.borrow().left.clone(), 2 * i + 1, res);
-    tree_to_vec_dfs(root.borrow().right.clone(), 2 * i + 2, res);
 }
 
 /* 将二叉树序列化为列表 */
 pub fn tree_to_vec(root: Option<Rc<RefCell<TreeNode>>>) -> Vec<Option<i32>> {
     let mut res = vec![];
-    tree_to_vec_dfs(root, 0, &mut res);
+    tree_to_vec_dfs(root.as_ref(), 0, &mut res);
     res
 }