May 30, 2022 · May 11, 2022 · May 11, 2022 · May 11, 2022 · May 12, 2022 · May 12, 2022
diff --git a/problems/0024.两两交换链表中的节点.md b/problems/0024.两两交换链表中的节点.md
Original file line number	Diff line number	Diff line change
Expand Up		@@ -311,7 +311,29 @@ func swapPairs(_ head: ListNode?) -> ListNode? {
		return dummyHead.next
		}
		```

	Scala:
	```scala
	// 虚拟头节点
	object Solution {
	def swapPairs(head: ListNode): ListNode = {
	var dummy = new ListNode(0, head) // 虚拟头节点
	var pre = dummy
	var cur = head
	// 当pre的下一个和下下个都不为空,才进行两两转换
	while (pre.next != null && pre.next.next != null) {
	var tmp: ListNode = cur.next.next // 缓存下一次要进行转换的第一个节点
	pre.next = cur.next // 步骤一
	cur.next.next = cur // 步骤二
	cur.next = tmp // 步骤三
	// 下面是准备下一轮的交换
	pre = cur
	cur = tmp
	}
	// 最终返回dummy虚拟头节点的下一个,return可以省略
	dummy.next
	}
	}
	```

		-----------------------
		<div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>