Leetcode 24 Swap Nodes in Pairs

Given a linked list, swap every two adjacent nodes and return its head.

For example,
Given 1->2->3->4, you should return the list as 2->1->4->3.

Your algorithm should use only constant space. You may not modify the values in the list, only nodes itself can be changed.

链表基本操作

1.设定第二个node为temp

2.连接第一个node下一个为第三个node

3.连接第二个node下一个为第一个node

4.连接起始的node为第二个node

5.指针右移两位

var swapPairs = function(head) {
    if (!head || !head.next) return head
    var dummy = new ListNode()
    dummy.next = head
    p = dummy
    while (p.next && p.next.next){
        temp = p.next.next
        p.next.next = temp.next
        temp.next = p.next
        p.next = temp
        p = p.next.next
    }
    return dummy.next
}