Java教程

Java在循环链接列表中搜索元素

在此程序中,我们创建了一个循环链接列表并搜索列表中的节点。
9->
5->
2->
7->
3
考虑上述示例。假设我们需要搜索节点5。要解决此问题,我们将遍历列表并将每个节点与5进行比较。如果找到匹配项,则将标志设置为true,并打印出节点5的位置。在此示例中,节点5位于位置2。

算法

定义一个代表列表中节点的Node类。它有两个属性数据,下一个将指向下一个节点。 定义另一个用于创建循环链表的类,它具有两个节点: head和tail。 search()将在列表中搜索一个节点: 变量i会跟踪搜索到的节点的位置。 变量标记将存储布尔值false。 当前将指向头节点。 通过将current递增到current.next并将i递增到i + 1来遍历循环。 将每个节点的数据与搜索到的节点进行比较。如果找到匹配项,则将标志设置为true。 如果flag为true,则打印搜索到的节点的位置。 否则,打印消息"列表中不存在元素"。

程序:

public class SearchNode {
    //Represents the node of list.
    public class Node{
        int data;
        Node next;
        public Node(int data) {
            this.data = data;
        }
    }
    //Declaring head and tail pointer as null.
    public Node head = null;
    public Node tail = null;
    //this function will add the new node at the end of the list.
    public void add(int data){
        //Create new node
        Node newNode = new Node(data);
        //Checks if the list is empty.
        if(head == null) {
            //if list is empty, both head and tail would point to new node.
            head = newNode;
            tail = newNode;
            newNode.next = head;
        }
        else {
            //tail will point to new node.
            tail.next = newNode;
            //New node will become new tail.
            tail = newNode;
            //Since, it is circular linked list tail will point to head.
            tail.next = head;
        }
    }
    //Searches for a node in the list
    public void search(int element) {
        Node current = head;
        int i = 1;
        boolean flag = false;
        //Checks whether list is empty
        if(head == null) {
            System.out.println("List is empty");
        }
        else {
            do{
                //Compares element to be found with each node present in the list
                if(current.data == element) {
                    flag = true;
                    break;
                }
                current = current.next;
                i++;
            }
            while(current != head);
            if(flag)
                 System.out.println("Element is present in the list at the position : " + i);
            else
                 System.out.println("Element is not present in the list");
        }
    }
    public static void main(String[] args) {
        SearchNode cl = new SearchNode();
        //Adds data to the list
        cl.add(1);
        cl.add(2);
        cl.add(3);
        cl.add(4);
        //Search for node 2 in the list
        cl.search(2);
        //Search for node in the list
        cl.search(7);
    }
}
输出:
Element is present in the list at the position: 2
Element is not present in the list
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