添加 0206.翻转链表 python3版本

Author: morningsky

problems/0206.翻转链表.md

@@ -143,7 +143,25 @@ class Solution {
 ```
 
 Python：
-
+```python
+#双指针
+# Definition for singly-linked list.
+# class ListNode:
+#     def __init__(self, val=0, next=None):
+#         self.val = val
+#         self.next = next
+class Solution:
+    def reverseList(self, head: ListNode) -> ListNode:
+        cur = head   
+        pre = None
+        while(cur!=None):
+            temp = cur.next # 保存一下 cur的下一个节点，因为接下来要改变cur->next
+            cur.next = pre #反转
+            #更新pre、cur指针
+            pre = cur
+            cur = temp
+        return pre
+```
 
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