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;
        }
    }
}