Update 0102.二叉树的层序遍历.md

problems/0102.二叉树的层序遍历.md

@@ -1224,6 +1224,39 @@ object Solution {
 }
 ```
 
+rust:
+
+```rust
+use std::cell::RefCell;
+use std::collections::VecDeque;
+use std::rc::Rc;
+impl Solution {
+    pub fn average_of_levels(root: Option<Rc<RefCell<TreeNode>>>) -> Vec<f64> {
+        let mut res = vec![];
+        let mut queue = VecDeque::new();
+        if root.is_some() {
+            queue.push_back(root);
+        }
+        while !queue.is_empty() {
+            let len = queue.len();
+            let mut sum = 0;
+            for _ in 0..len {
+                let node = queue.pop_front().unwrap().unwrap();
+                sum += node.borrow().val;
+                if node.borrow().left.is_some() {
+                    queue.push_back(node.borrow().left.clone());
+                }
+                if node.borrow().right.is_some() {
+                    queue.push_back(node.borrow().right.clone());
+                }
+            }
+            res.push((sum as f64) / len as f64);
+        }
+        res
+    }
+}
+```
+
 # 429.N叉树的层序遍历
 
 [力扣题目链接](https://leetcode.cn/problems/n-ary-tree-level-order-traversal/)