Insertion Sort List

Q:
Sort a linked list using insertion sort.
A:

/**
 * 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 header = new ListNode(Integer.MIN_VALUE);
        while(head!=null){
            ListNode tmp = head;
            head = head.next;
            
            ListNode runner = header;
            while(runner.next!=null && runner.next.val < tmp.val)
                runner = runner.next;
            
            tmp.next = runner.next;
            runner.next = tmp;
        }
        return header.next;
    }
}

Mistakes:
1: 当插入到比tail更前的的时候，  忘了break来跳出循环。
---------------第二遍--------------
1： 忘了把preNode 在whileloop的时候，先置为 newHeader
2：  after  checking preNode == null,    Mistakenly wrote
 tmp.next = preNode.next.next ;                        what the hell, can you make this mistake???????

Learned: