java数据结构之哈希表

哈希表(散列)-Google 上机题

package cn.ycl.dataStructures.HashTable;
import java.util.Scanner;
//哈希表
public class HashTableDemo{

public static void main(String[] args) {
//创建哈希表
HashTable hashTable = new HashTable(7);
//创建一个简单的菜单
Scanner scanner = new Scanner(System.in);
while (true) {
System.out.println("add:添加员工");
System.out.println("list:查询员工");
System.out.println("exit: 退出");
String key= scanner.next();
switch (key) {
case "add":
System.out.println("请输入id:");
int id=scanner.nextInt();
System.out.println("请输入name:");
String name= scanner.next();
Emp emp = new Emp(id ,name);
hashTable.add(emp);
break;
case "list":
hashTable.list();
break;
case "exit":
scanner.close();
System.exit(0);
break;
default:
break;
}


}


}
}

//创建HashTabble管理多条链表
class HashTable{
private int size;
private EmpLinkedList [] empLinkdedListArray;
//
public HashTable(int size) {
super();
this.size = size;
empLinkdedListArray=new EmpLinkedList[size];
for (int i = 0; i < size; i++) {
empLinkdedListArray[i]=new EmpLinkedList();
}
}
//添加员工
public void add(Emp emp) {
//根据员工id，判断该员工应该添加到那条链表中去
int num=selectLinkList(emp.id);
//将员工加入到对应的链表中
empLinkdedListArray[num].add(emp);
}
//显示员工
public void list() {
for (int i = 0; i < size; i++) {
empLinkdedListArray[i].list(i);
}

}

// 散列函数,使用简单的取模法
public int selectLinkList(int id) {
// 返回的取余代表将员工插入到哈希表中的哪个链表中
return id % size;
}

}

class Emp {
int id;
String name;
Emp next;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Emp getNext() {
return next;
}
public void setNext(Emp next) {
this.next = next;
}
public Emp() {
super();
}
public Emp(int id, String name) {
super();
this.id = id;
this.name = name;
}
}
class EmpLinkedList {
Emp head;
//添加员工
public void add(Emp emp) {
// 当前链表为空时
if (head == null) {
head= emp;
return;
}
Emp temp=head;
while (true) {
// 持续查找，直到找到链表末尾
if (temp.next==null) {
break;
}
temp=temp.next;
}
temp.next=emp;
}
// 遍历员工
public void list(int no) {
Emp temp = head;
if (head== null) {
System.out.println("第"+(no+1)+"条链表为空");
return;
}
System.out.print("第"+(no+1)+"条链表的信息为：");
while (true) {
System.out.printf("=>id=%d, name=%s\t", temp.id, temp.name);
System.out.println();
if (temp.next == null) {
break;
}
temp = temp.next;// 后移，遍历
}
}
}