L2807

lass Solution {
    public ListNode insertGreatestCommonDivisors(ListNode head) {
        if(head==null || head.next==null) return head;
        ListNode p=head;
        ListNode q=head.next;
        while(q!=null){					//注意下不是q.next
            int cur = func(p.val,q.val);
            // System.out.println(p.val+" "+q.val);
            ListNode tmp =new ListNode();
            tmp.next=p.next;
            p.next=tmp;
            tmp.val=cur;
            p=q;
            q=q.next;

        }
        return head;
    }
    public int func(int p, int q){			//无视p,q大小直接求gcd
        return q==0?p:func(q,p%q);
    }
}