Insertion Sort List 链表插入排序

地址：https://oj.leetcode.com/problems/insertion-sort-list/

public class Solution {
    	public ListNode insertionSortList(ListNode head) {
		if(head==null || head.next ==null){
			return head;
		}
		ListNode ans = new ListNode(head.val);
		ListNode pre = null;
		ListNode cur = ans;
		head = head.next;
		while(head!=null){
			cur = ans;
			pre = null;
			while(cur!=null &&  cur.val<head.val ){
				pre = cur;
				cur = cur.next;
			}
			if(pre == null){
				ListNode temp = new ListNode(head.val);
				temp.next = cur;
				ans = temp;
			}else {
				ListNode temp = new ListNode(head.val);
				pre.next = temp;
				temp.next = cur;
			}
			head = head.next;
		}
		return ans;
	}

}