You use n coupons, one at a time in the given order, on an item whose starting price is P won.
There are three kinds of coupons.
- "rate p": take p% off the current price. The amount taken off is current price × p ÷ 100 with everything below 1 won dropped.
- "cut k": take k won off the current price. If the price would go below 0 won, it becomes 0 won.
- "cap c": if the current price is more than c won it becomes c won; otherwise it stays.
The first line gives P and n, and the next n lines give the coupons, one per line, in the order they are used.
Each time you use a coupon, print the price after it, one per line.
Write a coupon interface with a single method apply that takes a price and returns the price after the coupon, and have three coupon classes implement it.
Put all the coupons in a list typed by the coupon interface, then go through the list in order and only call apply, without asking which kind each coupon is.
Input
1 ≤ P ≤ 1,000,000, 1 ≤ n ≤ 1,000, 0 ≤ p ≤ 100, 0 ≤ k, c ≤ 1,000,000 (all integers)
Output
n lines: the price after each coupon is used
Example 1 · stdin
12345 4
rate 10
cut 2000
cap 8999
rate 50
stdout
11111
9111
8999
4500
main.py
Error List00F8 ↓ · ⇧F8 ↑
Input (stdin)
When you run, these lines are fed to input()/stdin in order (the program doesn't stop to ask).
$ Ready
Open this on a computer to write and run code. On mobile you can read the problem and the solutions.
In other languagesShow solutions by language · 5 languages
This problem accepts only Python, TypeScript, Java, C# and C++, which have interfaces or syntax that plays that role. JavaScript uses duck typing (you just call a method if the name matches), so there is nowhere to write an interface, and C and Craykon have no classes. How you write down the promise "there is an apply" differs by language. TypeScript interface Coupon { apply(price: number): number } with class RateCoupon implements Coupon; Java interface Coupon with implements (the method must be public; this solution uses record to keep it short); C# interface ICoupon (by convention the name starts with I) with class RateCoupon : ICoupon; C++ inherits from an abstract class that has only the pure virtual function virtual int apply(int) const = 0; and marks overrides with override. Python writes "you must define this method" with abc.ABC and @abstractmethod (a class that leaves it out raises TypeError when you create an object). A TypeScript interface exists only for type checking and disappears from the running code. Four traps: ① In C++, if the base class method lacks virtual, calling through a Coupon pointer runs the base class version, not the derived one (static binding). Java and C# interface methods always run the implementation. ② In Java, C# and C++, dividing the rate first as in price * (p / 100) uses integer division, so it is 0 whenever p is below 100 and nothing is taken off. Multiply first, then divide. ③ What gets rounded down is the amount taken off. Rounding down the remaining price price * (100 - p) / 100 instead turns 10% off 999 won into 899 won instead of 900 won. ④ Guard cut with max(0, …) so the price never goes negative.
Pythonmain.py · 49 lines
import sysfrom abc import ABC, abstractmethodclass Coupon(ABC): """가격을 받아 쿠폰을 쓴 뒤의 가격을 돌려준다""" @abstractmethod def apply(self, price: int) -> int: ...class RateCoupon(Coupon): def __init__(self, p: int): self.p = p def apply(self, price: int) -> int: return price - price * self.p // 100 # 깎는 돈의 1원 아래를 버린다class CutCoupon(Coupon): def __init__(self, k: int): self.k = k def apply(self, price: int) -> int: return max(0, price - self.k)class CapCoupon(Coupon): def __init__(self, c: int): self.c = c def apply(self, price: int) -> int: return min(price, self.c)KINDS = {"rate": RateCoupon, "cut": CutCoupon, "cap": CapCoupon}lines = sys.stdin.read().split("\n")price, n = map(int, lines[0].split())coupons: list[Coupon] = []for i in range(1, n + 1): kind, value = lines[i].split() coupons.append(KINDS[kind](int(value)))out = []for c in coupons: # 어떤 쿠폰인지 묻지 않고 apply만 부른다 price = c.apply(price) out.append(price)print("\n".join(map(str, out)))
TypeScriptmain.ts · 49 lines
import { readFileSync } from "node:fs";// 가격을 받아 쿠폰을 쓴 뒤의 가격을 돌려준다interface Coupon { apply(price: number): number;}class RateCoupon implements Coupon { constructor(private readonly p: number) {} apply(price: number): number { return price - Math.floor((price * this.p) / 100); // 깎는 돈의 1원 아래를 버린다 }}class CutCoupon implements Coupon { constructor(private readonly k: number) {} apply(price: number): number { return Math.max(0, price - this.k); }}class CapCoupon implements Coupon { constructor(private readonly c: number) {} apply(price: number): number { return Math.min(price, this.c); }}function makeCoupon(kind: string, value: number): Coupon { if (kind === "rate") return new RateCoupon(value); if (kind === "cut") return new CutCoupon(value); return new CapCoupon(value);}const lines: string[] = readFileSync(0, "utf8").split("\n");const [first, count] = lines[0].trim().split(/\s+/).map(Number);const coupons: Coupon[] = [];for (let i = 1; i <= count; i++) { const [kind, value] = lines[i].trim().split(/\s+/); coupons.push(makeCoupon(kind, Number(value)));}let price = first;const out: number[] = [];for (const c of coupons) { price = c.apply(price); // 어떤 쿠폰인지 묻지 않고 apply만 부른다 out.push(price);}console.log(out.join("\n"));
JavaMain.java · 55 lines
import java.io.*;import java.util.*;public class Main { // 가격을 받아 쿠폰을 쓴 뒤의 가격을 돌려준다 interface Coupon { int apply(int price); } record RateCoupon(int p) implements Coupon { public int apply(int price) { return price - price * p / 100; // 곱하고 나서 나눈다: 깎는 돈의 1원 아래를 버린다 } } record CutCoupon(int k) implements Coupon { public int apply(int price) { return Math.max(0, price - k); } } record CapCoupon(int c) implements Coupon { public int apply(int price) { return Math.min(price, c); } } static Coupon makeCoupon(String kind, int value) { return switch (kind) { case "rate" -> new RateCoupon(value); case "cut" -> new CutCoupon(value); default -> new CapCoupon(value); }; } public static void main(String[] args) throws IOException { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); StringTokenizer st = new StringTokenizer(br.readLine()); int price = Integer.parseInt(st.nextToken()); int n = Integer.parseInt(st.nextToken()); List<Coupon> coupons = new ArrayList<>(); for (int i = 0; i < n; i++) { st = new StringTokenizer(br.readLine()); String kind = st.nextToken(); coupons.add(makeCoupon(kind, Integer.parseInt(st.nextToken()))); } StringBuilder sb = new StringBuilder(); for (Coupon c : coupons) { price = c.apply(price); // 어떤 쿠폰인지 묻지 않고 apply만 부른다 sb.append(price).append('\n'); } System.out.print(sb); }}
C#Main.cs · 60 lines
using System;using System.Collections.Generic;using System.Text;// 가격을 받아 쿠폰을 쓴 뒤의 가격을 돌려준다interface ICoupon{ int Apply(int price);}class RateCoupon : ICoupon{ private readonly int p; public RateCoupon(int p) { this.p = p; } public int Apply(int price) => price - price * p / 100; // 곱하고 나서 나눈다: 깎는 돈의 1원 아래를 버린다}class CutCoupon : ICoupon{ private readonly int k; public CutCoupon(int k) { this.k = k; } public int Apply(int price) => Math.Max(0, price - k);}class CapCoupon : ICoupon{ private readonly int c; public CapCoupon(int c) { this.c = c; } public int Apply(int price) => Math.Min(price, c);}class Program{ static ICoupon MakeCoupon(string kind, int value) => kind switch { "rate" => new RateCoupon(value), "cut" => new CutCoupon(value), _ => new CapCoupon(value), }; static void Main() { var first = Console.ReadLine()!.Split(' ', StringSplitOptions.RemoveEmptyEntries); int price = int.Parse(first[0]), n = int.Parse(first[1]); var coupons = new List<ICoupon>(); for (int i = 0; i < n; i++) { var parts = Console.ReadLine()!.Split(' ', StringSplitOptions.RemoveEmptyEntries); coupons.Add(MakeCoupon(parts[0], int.Parse(parts[1]))); } var sb = new StringBuilder(); foreach (ICoupon c in coupons) { price = c.Apply(price); // 어떤 쿠폰인지 묻지 않고 Apply만 부른다 sb.Append(price).Append('\n'); } Console.Write(sb); }}
C++main.cpp · 51 lines
#include <algorithm>#include <iostream>#include <memory>#include <string>#include <vector>// C++의 인터페이스: 순수 가상 함수만 가진 추상 클래스struct Coupon { virtual int apply(int price) const = 0; virtual ~Coupon() = default; // 기반 포인터로 지워도 파생 소멸자가 불리게};struct RateCoupon : Coupon { int p; explicit RateCoupon(int p) : p(p) {} int apply(int price) const override { return price - price * p / 100; } // 깎는 돈의 1원 아래를 버린다};struct CutCoupon : Coupon { int k; explicit CutCoupon(int k) : k(k) {} int apply(int price) const override { return std::max(0, price - k); }};struct CapCoupon : Coupon { int c; explicit CapCoupon(int c) : c(c) {} int apply(int price) const override { return std::min(price, c); }};std::unique_ptr<Coupon> makeCoupon(const std::string& kind, int value) { if (kind == "rate") return std::make_unique<RateCoupon>(value); if (kind == "cut") return std::make_unique<CutCoupon>(value); return std::make_unique<CapCoupon>(value);}int main() { int price, n; std::cin >> price >> n; std::vector<std::unique_ptr<Coupon>> coupons; for (int i = 0; i < n; i++) { std::string kind; int value; std::cin >> kind >> value; coupons.push_back(makeCoupon(kind, value)); } for (const auto& c : coupons) { price = c->apply(price); // 어떤 쿠폰인지 묻지 않고 apply만 부른다 std::cout << price << "\n"; }}