Group into Lists

Lab Java Intermediate 20 points

Read lines department name. Build a TreeMap<String, List<String>> and print each department with its names sorted.

Input

n, then n lines.

Output

One line per department: dept: [names]

Example

Input

5
sales zoe
it amy
sales bob
hr cy
it dan

Output

hr: [cy]
it: [amy, dan]
sales: [bob, zoe]

Sample input available Sample output available

Editor

Java

Hints

Create the list the first time a department appears.

computeIfAbsent(dept, k -> new ArrayList<>()) is the Java 8 shortcut.

Solution explanation

A map from key to list is the standard way to group data.

Show solution

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.TreeMap;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Map<String, List<String>> byDept = new TreeMap<String, List<String>>();
        for (int i = 0; i < n; i++) {
            String dept = sc.next();
            String name = sc.next();
            List<String> list = byDept.get(dept);
            if (list == null) {
                list = new ArrayList<String>();
                byDept.put(dept, list);
            }
            list.add(name);
        }
        for (Map.Entry<String, List<String>> e : byDept.entrySet()) {
            Collections.sort(e.getValue());
            System.out.println(e.getKey() + ": " + e.getValue());
        }
    }
}

Output

Answer