添加py和js

animation-simulation/链表篇/面试题 02.03. 链表中间节点.md

@@ -71,6 +71,7 @@ class Solution {
 C++ Code:
 
 ```cpp
+class Solution {
 public:
     ListNode* middleNode(ListNode* head) {
         ListNode * fast = head;//快指针
@@ -86,3 +87,34 @@ public:
 };
 ```
 
+JS Code:
+
+```js
+var middleNode = function(head) {
+    let fast = head;//快指针
+    let slow = head;//慢指针
+    //循环条件，思考一下跳出循环的情况
+    while (fast && fast.next) {
+        fast = fast.next.next;
+        slow = slow.next;
+    }
+    //返回slow指针指向的节点
+    return slow
+};
+```
+
+Python Code:
+
+```py
+class Solution:
+    def middleNode(self, head: ListNode) -> ListNode:
+        fast = head  # 快指针
+        slow = head  # 慢指针
+        # 循环条件，思考一下跳出循环的情况
+        while fast is not None and fast.next is not None:
+            fast = fast.next.next
+            slow = slow.next
+        # 返回slow指针指向的节点
+        return slow
+```
+