leetcode-004 insertion sort list

 package leetcode;

 class ListNode {
     int val;
     ListNode next;

     ListNode(int x) {
         val = x;
         next = null;
     }
 }

 public class insertionsortlist {
     public static ListNode insertionSortList(ListNode head) {
         ListNode h = new ListNode(0);
         h.next = head;
         ListNode pre = h;
         ListNode be = head;
         ListNode af;
         ListNode po;

         if(be==null||be.next==null)
             return head;
         af=be.next;
         be.next=null;
         while(af!=null){
             po=af.next;
             pre=h;
             be=h.next;
             while (be != null && be.val <= af.val) {
                 pre = be;
                 be = be.next;
             }
             if(be==null){
                 pre.next=af;
                 af.next=null;
             }else{
                 pre.next = af;
                 af.next = be;
             }
             af=po;
         }
         return h.next;
     }
     public static void main(String[] args) {
         ListNode a = new ListNode(2);
         ListNode b = new ListNode(1);
         ListNode c = new ListNode(4);
         a.next=b;
         b.next = c;
         c.next = null;
         ListNode p = insertionSortList(a);
         while (p != null) {
             System.out.println(p.val);
             p = p.next;
         }
     }
 }