Inventory Report

Lab Java Advanced 30 points

Read products name category qty price. Print, per category (sorted), the number of products and the stock value (2 decimals), then the overall most valuable product. Use streams with groupingBy.

Input

n, then n lines.

Output

One line per category, then top: NAME VALUE.

Example

Input

4
pen office 100 1.5
desk office 2 120
apple food 50 0.4
laptop tech 3 899.99

Output

food 1 20.00
office 2 390.00
tech 1 2699.97
top: laptop 2699.97

Sample input available Sample output available

Editor

Java

Hints

groupingBy into a TreeMap keeps categories sorted.

max(Comparator) returns an Optional - call get() when you know the list isn't empty.

Solution explanation

Streams turn a reporting task into a few declarative steps.

Show solution

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.TreeMap;
import java.util.stream.Collectors;

class Product {
    final String name, category;
    final int qty;
    final double price;

    Product(String name, String category, int qty, double price) {
        this.name = name;
        this.category = category;
        this.qty = qty;
        this.price = price;
    }

    double value() {
        return qty * price;
    }
}

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        List<Product> products = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            products.add(new Product(sc.next(), sc.next(), sc.nextInt(), sc.nextDouble()));
        }
        Map<String, List<Product>> byCategory = products.stream()
                .collect(Collectors.groupingBy(p -> p.category, TreeMap::new, Collectors.toList()));
        byCategory.forEach((cat, list) -> System.out.printf("%s %d %.2f%n", cat, list.size(),
                list.stream().mapToDouble(Product::value).sum()));
        Product top = products.stream().max(Comparator.comparingDouble(Product::value)).get();
        System.out.printf("top: %s %.2f%n", top.name, top.value());
    }
}

Output

Answer