[数据结构与算法]LeetCode_两两交换链表中的节点_C#_迭代

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     public int val;
 *     public ListNode next;
 *     public ListNode(int val=0, ListNode next=null) {
 *         this.val = val;
 *         this.next = next;
 *     }
 * }
 */
public class Solution {
    public ListNode SwapPairs(ListNode head) {
            if (head == null)
                return null;
            int x = 1;//用来判断head是奇数还是偶数
            int temp = 0;
            //在遍历head的同时给temp_2赋值，最后返回的结果是result
            ListNode temp_2 = new ListNode();
            ListNode result = temp_2;
            while (null != head)
            {
                if (x % 2 != 0)
                {
                    temp = head.val;
                    head = head.next;
                    if(head != null)
                    {
                        temp_2.val = head.val;
                        temp_2.next = new ListNode();
                        temp_2 = temp_2.next;
                        temp_2.val = temp;
                    }
                    else
                    {
                        temp_2.val = temp;
                    }
                }
                else
                {
                    head = head.next;
                    if(null != head)
                    {
                        temp_2.next = new ListNode();
                        temp_2 = temp_2.next;
                    }
                }
                x++;
            }
            return result;
    }
}