线下编程机试题一枚。

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Scanner;
import java.util.regex.Pattern;

public class Main {
    private static HashMap<Integer, Employee> map = new HashMap<Integer, Employee>();

    public static void main(String[] args) throws IOException {
        // load file into map
        System.out.println("File loading...");
        loadFile();
        System.out.println("File load succeed.");
        System.out.println("Please input employee's id:");
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()) {
            String temp = sc.next();
            if (temp.equals("exit")) {
                System.out.println("Exit succeed.");
                break;
            } else if (temp.equals("All")) {
                System.out.println("All employees:");
                showAll();
            } else if (checkIdLegal(temp)) {
                int id = Integer.parseInt(temp);
                if (findId(id)) {
                    Employee e = map.get(id);
                    e.print();
                } else {
                    System.out.println("This id is not exist.");
                    System.out.println("Please input employee's id:");
                }
            } else {
                System.out.println("Your input is illegal.");
                System.out.println("Please input employee's id:");
            }
        }
        sc.close();
    }
    
    // check if the id is exist. 
    private static boolean findId(int id) {
        if (map.containsKey(id)) {
            return true;
        }
        return false;
    }

    // check if the input id is numeric.
    private static boolean checkIdLegal(String temp) {
        Pattern pattern = Pattern.compile("[0-9]*");
        return pattern.matcher(temp).matches();
    }

    // show all employees' information.
    private static void showAll() {
        // find the leader first.
        Iterator<Map.Entry<Integer, Employee>> it = map.entrySet().iterator();
        ArrayList<Employee> leaders = new ArrayList<Employee>();
        while (it.hasNext()) {
            Map.Entry<Integer, Employee> entry = it.next();
            Employee e = entry.getValue();
            if (e.getSupId() == 0) {
                leaders.add(e);
            }
        }
        Collections.sort(leaders);
        for (int i = 0; i < leaders.size(); i++) {
            Employee leader = leaders.get(i);
            leader.printName();
            showSub(leader, 1);
        }
    }

    private static void showSub(Employee e, int tab) {
        ArrayList<Integer> subList = e.getSubId();
        ArrayList<Employee> subEmployees = new ArrayList<Employee>();
        for (int i = 0; i < subList.size(); i++) {
            subEmployees.add(map.get(subList.get(i)));
        }
        Collections.sort(subEmployees);
        for (int i = 0; i < subEmployees.size(); i++) {
            Employee subEmployee = subEmployees.get(i);
            for (int j = 0; j < tab; j++) {
                System.out.print("\t");
            }
            subEmployee.printName();
            showSub(subEmployee, tab + 1);
        }
    }

    // load file into map.
    private static void loadFile() throws FileNotFoundException, IOException {
        String filePath = "C:/Users/chenyangwang/Downloads/data.txt";
        FileInputStream fis = new FileInputStream(filePath);
        InputStreamReader isr = new InputStreamReader(fis);
        BufferedReader br = new BufferedReader(isr);
        String str = "";
        while ((str = br.readLine()) != null) {
            String[] strLine = str.split(",");
            for (int i = 0; i < strLine.length; i++) {
                strLine[i] = strLine[i].trim();
            }
            // if the employee has no superior, is a leader.
            if (strLine.length == 3) {
                String name = strLine[0];
                int id = Integer.parseInt(strLine[1]);
                int age = Integer.parseInt(strLine[2]);
                // see if the map contains the employee.
                if (map.containsKey(id)) {
                    Employee e = map.get(id);
                    e.setName(name);
                    e.setId(id);
                    e.setAge(age);
                    e.setSupId(0);
                    map.put(id, e);
                } else {
                    Employee e = new Employee(name, id, age, 0);// make the leader's supId 0.
                    map.put(id, e);
                }
            } else {
                // the employee has a superior.
                String name = strLine[0];
                int id = Integer.parseInt(strLine[1]);
                int age = Integer.parseInt(strLine[2]);
                int supId = Integer.parseInt(strLine[3]);
                // see if the map contains the employee.
                if (map.containsKey(id)) {
                    Employee e = map.get(id);
                    e.setName(name);
                    e.setId(id);
                    e.setAge(age);
                    e.setSupId(supId);
                    map.put(id, e);
                } else {
                    Employee e = new Employee(name, id, age, supId);
                    map.put(id, e);
                }
                // update the superior's subId. if not exist, create it.
                if (map.containsKey(supId)) {
                    Employee superior = map.get(supId);
                    superior.addSubId(id);
                    map.put(supId, superior);
                } else {
                    Employee superior = new Employee("", -1, -1, -1);
                    superior.addSubId(id);
                    map.put(supId, superior);
                }
            }
        }
        br.close();
    }
}

import java.util.ArrayList;

public class Employee implements Comparable<Employee>{
    private String name;
    private int id;
    private int age;
    private int supId;
    private ArrayList<Integer> subId;

    public Employee(String name, int id, int age, int supId) {
        this.name = name;
        this.id = id;
        this.age = age;
        this.supId = supId;
        this.subId = new ArrayList<Integer>();
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public int getSupId() {
        return supId;
    }

    public void setSupId(int supId) {
        this.supId = supId;
    }

    public ArrayList<Integer> getSubId() {
        return subId;
    }

    public void setSubId(ArrayList<Integer> subId) {
        this.subId = subId;
    }

    public void addSubId(Integer id) {
        this.subId.add(id);
    }

    // output the employee's information.
    public void print() {
        System.out.println("Name:" + this.name + " Id:" + this.id + " Age:" + this.age + " SupId:" + this.supId);
    }
    
    // output the employee's name.
    public void printName(){
        System.out.println(this.name);
    }

    // sort by name.
    @Override
    public int compareTo(Employee e) {
        return this.getName().compareTo(((Employee) e).getName());
    }

}