LinkList.java

public class LinkList {

    class Node {
        int data;
        Node next;

        Node(int d) {
            data = d;
            next = null;
        }
    }

    Node head;
    public LinkList() {
        head = null;
    }

    public void addFirst(int x) {
        Node n = new Node(x);
        n.next = head;
        head = n;
    }

    public void addLast(int x) {
        Node n = new Node(x);

        if (head == null) {
            head = n;
            return;
        }

        Node cur = head;
        while (cur.next != null) {
            cur = cur.next;
        }
        cur.next = n;
    }

    public void delete(int x) {
        if (head == null)
            return;

        if (head.data == x) {
            head = head.next;
            return;
        }

        Node cur = head;
        while (cur.next != null && cur.next.data != x) {
            cur = cur.next;
        }

        if (cur.next != null) {
            cur.next = cur.next.next;
        }
    }


    public void printList() {
        Node cur = head;
        while (cur != null) {
            System.out.print(cur.data + " ");
            cur = cur.next;
        }
        System.out.println();
    }

    public int size() {
        int cnt = 0;
        Node cur = head;
        while (cur != null) {
            cnt++;
            cur = cur.next;
        }
        return cnt;
    }

}