import java.util.Random;

/**
 * @Auther: Arsenal
 * @Date: 2020-03-23 19:13
 * @Description: 哈希表
 */
public class HashTable {
    public static void main(String[] args) {
        EmpHashTable empHashTable = new EmpHashTable(6);
        /*for (int i = 0; i < 10; i++) {
            Emp emp = new Emp(i, "老王" + i);
            empHashTable.addEmp(emp);
        }
        empHashTable.list();
        System.out.println("=============================");
        //empHashTable.findEmpById(8);
        empHashTable.delEmpById(18);
        empHashTable.list();*/
        /*for (int i = 30; i > 0; i--) {
            Emp emp = new Emp(i, "老王" + i);
            empHashTable.addEmpByOrder(emp);
        }
        empHashTable.list();*/

        for (int i = 0; i < 20; i++) {
            int id = new Random().nextInt(40);
            Emp emp = new Emp(id, "老王" + i);
            //empHashTable.addEmp(emp);
            empHashTable.addEmpByOrder(emp);
        }
        empHashTable.list();

    }
}

/**
 * hash表
 */
class EmpHashTable {
    public EmpLinkedList[] empLinkedList;
    private int size;

    // 初始化hashTable
    public EmpHashTable(int size) {
        this.size = size;
        this.empLinkedList = new EmpLinkedList[size];
        // 初始化链表
        for (int i = 0; i < size; i++) {
            empLinkedList[i] = new EmpLinkedList();
        }
    }

    /**
     * 添加雇员
     * @param emp 雇员
     */
    public void addEmp(Emp emp) {
        int empLinkedListNo = hashFunction(emp.id);
        empLinkedList[empLinkedListNo].addEmp(emp);
    }

    /**
     * 按顺序添加雇员
     * @param emp 雇员
     */
    public void addEmpByOrder(Emp emp) {
        int empLinkedListNo = hashFunction(emp.id);
        empLinkedList[empLinkedListNo].addEmpByOrder(emp);
    }

    /**
     * 根据id删除雇员
     * @param id 雇员id
     */
    public void delEmpById(int id) {
        int empLinkedListNo = hashFunction(id);
        empLinkedList[empLinkedListNo].delEmpById(id);
    }

    /**
     * 遍历hashtable
     */
    public void list() {
        for (int i = 0; i < size; i++) {
            System.out.println("======第" + (i + 1) + "个子链表======");
            empLinkedList[i].list();
        }
    }

    /**
     * 根据id查询雇员
     * @param id 雇员id
     * @return 雇员
     */
    public void findEmpById(int id) {
        int empLinkedListNo = hashFunction(id);
        Emp emp = empLinkedList[empLinkedListNo].findEmpById(id);
        if (emp != null) {
            System.out.println("该雇员在" + (empLinkedListNo + 1) + "条链表上");
            System.out.println(emp);
        } else {
            System.out.println("没有该雇员");
        }
    }

    // 散列函数，简单取模
    public int hashFunction(int id) {
        return id % size;
    }
}

/**
 * 链表
 */
class EmpLinkedList {
    private Emp head;

    /**
     * 添加雇员(直接添加到末尾)
     * @param emp 雇员
     */
    public void addEmp(Emp emp) {
        if (head == null) {
            head = emp;
            return;
        }
        // 查找最后一个节点
        Emp cur = head;
        while (cur.next != null) {
            cur = cur.next;
        }
        cur.next = emp;
    }

    /**
     * 按顺序添加雇员
     * @param emp 雇员
     */
    public void addEmpByOrder(Emp emp) {
        if (head == null) {
            head = emp;
            return;
        }
        Emp cur = head;

        while (cur != null) {

            if (head.id > emp.id) { //比第一个节点还小，插入第一个
                Emp temp = head;
                head = emp;
                emp.next = temp;
                break;
            } else if (cur.id == emp.id) {
                System.out.println("编号为" + emp.id + "的节点已经存在");
                break;
            } else if (cur.next == null) {//末尾情况
                cur.next = emp;
                break;
            } else if (cur.next.id > emp.id) { //中间的情况
                emp.next = cur.next;
                cur.next = emp;
                break;
            }
            cur = cur.next;
        }
    }

    /**
     * 根据id删除雇员
     * @param id 雇员id
     */
    public void delEmpById(int id) {
        if (head == null) {
            System.out.println("该链表为空");
            return;
        }

        Emp cur = head;
        boolean flag = false; //是否找到该节点的标志
        while (true) {

            if (cur.next == null) {
                break; //没有找到，退出
            }

            if (cur.next.id == id) {
                //找到了
                flag = true;
                break;
            }
            cur = cur.next;
        }

        //删除
        if (flag) {
            cur.next = cur.next.next;
        } else {
            System.out.println("不存在该节点");
        }
    }

    /**
     * 遍历链表
     */
    public void list() {
        if (head == null) {
            System.out.println("该链表为空");
            return;
        }
        Emp cur = head;
        while (true) {
            System.out.println(cur);
            if (cur.next == null) {
                break;
            }
            cur = cur.next;
        }

    }

    /**
     * 根据id查询雇员
     * @param id 雇员id
     * @return 如果有则返回该雇员，否则返回null
     */
    public Emp findEmpById(int id) {
        if (head == null) {
            System.out.println("链表为空");
            return null;
        }

        Emp cur = head;
        while (true) {
            if (cur.id == id) {
                break;
            }

            // 没有找到
            if (cur.next == null) {
                cur = null;
                break;
            }
            cur = cur.next;
        }
        return cur;
    }
}

/**
 * 节点
 */
class Emp {
    public int id;
    public String name;
    public Emp next;

    public Emp(int id, String name) {
        this.id = id;
        this.name = name;
    }

    @Override
    public String toString() {
        return "Emp{" + "id=" + id + ", name='" + name + '\'' + '}';
    }
}