[算法]按照左右半区的方式重新整合单链表

class Test{
    public static void main(String[] args) {
        Node head=new Node(1);
        head.next=new Node(2);
        head.next.next=new Node(3);
        head.next.next.next=new Node(4);
        head.next.next.next.next=new Node(5);
        head.next.next.next.next.next=new Node(6);
        head.next.next.next.next.next.next=new Node(7);
        print(head);
        merge(head);
        System.out.println();
        print(head);
    }
    public static void merge(Node head){
        if (head==null||head==null||head.next==null) {
            return;        
        }
        Node mid=head;
        Node cur=head.next;
        while(cur.next!=null&&cur.next.next!=null){
            mid=mid.next;
            cur=cur.next.next;
        }
        Node right=mid.next;
        mid.next=null;
        Node left=head;
        Node next=null;
        while(left.next!=null){
            next=right.next;
            right.next=left.next;
            left.next=right;
            left=right.next;
            right=next;
        }
        left.next=right;


    }
    public static void print(Node head){
        Node cur=head;
        while(cur!=null){
            System.out.print(cur.value+"   ");
            cur=cur.next;
        }
    }
    static class Node{
        public int value;
        public Node next;
        public Node(int value){
                this.value=value;
        }
    }
}