JZ25 合并两个排序的链表 Java

    public ListNode Merge (ListNode pHead1, ListNode pHead2) {
        if(pHead1==null)
            return pHead2;
        if(pHead2==null)
            return pHead1;
        
        ListNode dummy = new ListNode(-1);
        ListNode cur = dummy;

        while(pHead1!=null && pHead2!=null) {
            if(pHead1.val <= pHead2.val){
                cur.next = pHead1;
                // 只移动被取值的指针
                pHead1 = pHead1.next;
            }else{
                cur.next = pHead2;
                pHead2 = pHead2.next;
            }
            cur = cur.next;
        }
        if(pHead1!=null)
            cur.next = pHead1;
        else if(pHead2!=null)
            cur.next = pHead2;

        return dummy.next; // 图中 -1 是不是不用返回，所以返回next
    }