147. Insertion Sort List

Sort a linked list using insertion sort.

思路：插入排序，就是把node插入到左边的链表中。用一个dummynode来构造左边的链表。要是比最左边的数还小，就插到最左边也就是dummy.next。如果不是，则linear search左边的链表插入。

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode insertionSortList(ListNode head) {
        ListNode dummy=new ListNode(-1);
        
        while(head!=null)
    {
        ListNode cur=head;
        head=head.next;
        
        ListNode target=dummy;
        while(target.next!=null&&target.next.val<cur.val)
        {
            target=target.next;;
        }
        cur.next=target.next;
        target.next=cur;
    }
    return dummy.next;
    }
}