合并两个 Sorted Lnkedlist 并在新的linkedlist 中打印

Question

我正在尝试编写代码来合并两个排序列表并在另一个列表中显示。

我创建了一个函数“合并”，它将每个列表的头部作为它的两个参数并返回新列表的头部。我创建了一个“显示”函数，它采用“列表的头部”来显示其中的内容. 问题是当我试图显示新 List 的内容时，它什么也不显示。 这是我的主要功能。

public class Main {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Linkedlist o=new Linkedlist();
        Linkedlist o1=new Linkedlist();
        Linkedlist o2=new Linkedlist();

        o.insertAtlast(5);
        o.insertAtlast(10);
        o.insertAtlast(15);

        o1.insertAtlast(2);
        o1.insertAtlast(3);
        o1.insertAtlast(20);

        o2.head=o2.mergeList(o.head, o1.head);
        o2.Display(o2.head);

    }

}

and this is my Linkedlist Class

public class Linkedlist {

    static class Node{
        int data;
        Node link;
        public Node(int data) {
            this.data=data;
            this.link=null;
        }
    }

    Node head=null;

    public void insertAtlast(int data) {
        Node node=new Node(data);

        if(head==null)
            head=node;
        else
        {
            Node ptr=head;

            while(ptr.link!=null)
                ptr=ptr.link;
            ptr.link=node;
        }


    }


    public void Display(Node node) {
        while(node!=null) {
            System.out.println(node.data);
            node=node.link;
        }
    }




    public Node mergeList(Node head1,Node head2) {
        Node head3=null;

        if(head1==null)
            head=head2;
        else if(head2==null)
                head=head1;
        else {
            while(head1!=null && head2!=null) {

                if(head==null) {
                    if(head2.data<head1.data) {
                        Node node=new Node(head2.data);
                        head=node;
                        head2=head2.link;
                    }
                    else {
                        Node node=new Node(head1.data);
                        head=node;
                        head1=head1.link;
                    }
                }

                else
                {
                  head3=head;
                  while(head3.link!=null)
                      head=head3.link;
                  if(head2.data<head1.data) {
                      Node node=new Node(head2.data);
                      head3.link=node;
                      head2=head2.link;
                  }
                  else {
                      Node node=new Node(head1.data);
                      head3.link=node;
                      head1=head1.link;
                  }
                }

            }

        }

        return head;

    }

}

Answer 1

递归合并：

public Node mergeList(Node head1, Node head2) {
    if (head1 == null) return head2;
    if (head2 == null) return head1;

    if (head1.data < head2.data) {
        head1.link = mergeList(head1.link, head2);
        return head1;
    } else {
        head2.link = mergeList(head2.link, head1);
        return head2;
    }
}

迭代合并：

public Node mergeList(Node head1, Node head2) {

    Node head3 = null, cursor = null, cursorH1 = head1, cursorH2 = head2;

    while (cursorH1 != null && cursorH2 != null) {
        Node temp;

        if (cursorH1.data < cursorH2.data) {
            temp = cursorH1;
            cursorH1 = cursorH1.link;
        } else {
            temp = cursorH2;
            cursorH2 = cursorH2.link;
        }

        if (head3 == null) {
            cursor = temp;
            head3 = cursor;
        } else {
            cursor.link = temp;
            cursor = cursor.link;
        }
    }

    if (cursorH1 != null) {
        if (head3 == null) {
            head3 = cursorH1;
        } else {
            cursor.link = cursorH1;
        }
    }

    if (cursorH2 != null) {
        if (head3 == null) {
            head3 = cursorH2;
        } else {
            cursor.link = cursorH2;
        }
    }

    return head3;
}