编程题—对链表进行插入排序

思路：新建一个链表， 遍历原链表，将节点插入新链表正确的位置上面

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
import java.util.List;
import java.util.LinkedList;

public class Solution {
    public ListNode insertionSortList(ListNode head) {
        ListNode dummy = new ListNode(-1);
 
        while(head != null){

            //定义一个指针节点,找到当前节点在新链表中的正确位置
            ListNode node = dummy;
 
            while(node.next != null && node.next.val < head.val){
                node = node.next;
            }
             //记录head.next
            ListNode temp = head.next;
            
            head.next = node.next;  
            node.next = head;  
            
            //恢复head.next
            head = temp;
        }
 
        return dummy.next;
    }
}