Update 25.reverse-nodes-in-k-groups-cn.md

Author: azl397985856

problems/25.reverse-nodes-in-k-groups-cn.md

@@ -157,22 +157,28 @@ class Solution:
             count += 1
             if count % k == 0:
                 start = self.reverse(start, end.next)
+                # end 调到下一个
                 end = start.next
             else:
                 end = end.next
         return dummy.next
+    # (start, end） 左右都开放
 
     def reverse(self, start, end):
         prev, curr = start, start.next
         first = curr
+        # 反转
         while curr != end:
-            temp = curr.next
+            next = curr.next
             curr.next = prev
             prev = curr
-            curr = temp
+            curr = next
+        # 将反转后的链表添加到原链表中
         start.next = prev
-        first.next = curr
+        first.next = end
+        # 返回反转前的头， 也就是反转后的尾部
         return first
+
 ```
 
 *javascript code*
@@ -250,4 +256,4 @@ var reverseKGroup = function(head, k) {
 3. 翻转步骤#2链表： `1->2->5->4->3->8->7->6`
 
 ## 类似题目
-- [Swap Nodes in Pairs](https://leetcode.com/problems/swap-nodes-in-pairs/)
+- [Swap Nodes in Pairs](https://leetcode.com/problems/swap-nodes-in-pairs/)