Every item in the shop starts with a stock of 0. The first line gives the number of commands m, and each of the next m lines gives one command.
- "add item k": add k to that item's stock.
- "sell item k": if the stock is at least k, subtract k. Otherwise (including an item that has never been added) leave the stock unchanged and print "fail".
- "show item": print the item's current stock (0 if it has never been added).
After processing all commands, print on the last line the number of distinct items whose stock is 1 or more.
Input
1 ≤ m ≤ 2000, 1 ≤ k ≤ 1000. Item names are 1 to 12 lowercase English letters
Output
one line per "fail" or show result, in command order, then a last line with the number of items still in stock
Example 1 · stdin
7
add pen 3
add cup 2
sell pen 2
sell cup 5
show pen
show ink
sell cup 2
stdout
fail
1
0
1
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 · 8 languages
The trap is an item seen for the first time. Python stock[item] += k raises KeyError, C# stock[item] += k throws KeyNotFoundException, and Java int have = stock.get(item) unboxes null and throws NullPointerException. Read with a default: Python stock.get(item, 0), Java getOrDefault or merge(item, k, Integer::sum), C# GetValueOrDefault, JS Map with get(item) ?? 0. With a plain JS object {}, stock[item] || 0 picks up a function from Object.prototype for "constructor" and turns into a garbage string. C++ stock[item] += k inserts 0 for a missing key, so it just works (but even a read creates the key). The last line has its own trap: an item sold down to 0 is still in the map, so count only values of 1 or more, not len(stock). C has no map, so it searches a name/count table from the start. Craykon asks stock.Contains(item) on a Dict() first, and at the end walks stock.Values to count.
Pythonmain.py · 20 lines
import syslines = sys.stdin.read().split("\n")m = int(lines[0])stock = {}for line in lines[1:m + 1]: parts = line.split() cmd, item = parts[0], parts[1] have = stock.get(item, 0) if cmd == "add": stock[item] = have + int(parts[2]) elif cmd == "sell": k = int(parts[2]) if have >= k: stock[item] = have - k else: print("fail") else: print(have)print(sum(1 for v in stock.values() if v > 0))
JavaScriptmain.js · 15 lines
const lines = require("fs").readFileSync(0, "utf8").split("\n");const m = Number(lines[0]);const stock = new Map();const out = [];for (let i = 1; i <= m; i++) { const [cmd, item, k] = lines[i].trim().split(" "); const have = stock.get(item) ?? 0; if (cmd === "add") stock.set(item, have + Number(k)); else if (cmd === "sell") { if (have >= Number(k)) stock.set(item, have - Number(k)); else out.push("fail"); } else out.push(have);}out.push([...stock.values()].filter((v) => v > 0).length);console.log(out.join("\n"));
TypeScriptmain.ts · 16 lines
import { readFileSync } from "node:fs";const lines: string[] = readFileSync(0, "utf8").split("\n");const m: number = Number(lines[0]);const stock = new Map<string, number>();const out: (string | number)[] = [];for (let i = 1; i <= m; i++) { const [cmd, item, k] = lines[i].trim().split(" "); const have: number = stock.get(item) ?? 0; if (cmd === "add") stock.set(item, have + Number(k)); else if (cmd === "sell") { if (have >= Number(k)) stock.set(item, have - Number(k)); else out.push("fail"); } else out.push(have);}out.push([...stock.values()].filter((v) => v > 0).length);console.log(out.join("\n"));
JavaMain.java · 30 lines
import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.util.HashMap;import java.util.Map;public class Main { public static void main(String[] args) throws IOException { BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); int m = Integer.parseInt(in.readLine().trim()); Map<String, Integer> stock = new HashMap<>(); StringBuilder out = new StringBuilder(); for (int i = 0; i < m; i++) { String[] p = in.readLine().trim().split(" "); int have = stock.getOrDefault(p[1], 0); if (p[0].equals("add")) { stock.merge(p[1], Integer.parseInt(p[2]), Integer::sum); } else if (p[0].equals("sell")) { int k = Integer.parseInt(p[2]); if (have >= k) stock.put(p[1], have - k); else out.append("fail").append('\n'); } else { out.append(have).append('\n'); } } long inStock = stock.values().stream().filter(v -> v > 0).count(); out.append(inStock).append('\n'); System.out.print(out); }}
C#Main.cs · 32 lines
using System;using System.Collections.Generic;using System.Linq;class Program{ static void Main() { int m = int.Parse(Console.ReadLine()); var stock = new Dictionary<string, int>(); for (int i = 0; i < m; i++) { string[] p = Console.ReadLine().Trim().Split(' '); int have = stock.GetValueOrDefault(p[1]); if (p[0] == "add") { stock[p[1]] = have + int.Parse(p[2]); } else if (p[0] == "sell") { int k = int.Parse(p[2]); if (have >= k) stock[p[1]] = have - k; else Console.WriteLine("fail"); } else { Console.WriteLine(have); } } Console.WriteLine(stock.Values.Count(v => v > 0)); }}
C++main.cpp · 31 lines
#include <iostream>#include <string>#include <unordered_map>int main() { int m; std::cin >> m; std::unordered_map<std::string, int> stock; for (int i = 0; i < m; i++) { std::string cmd, item; std::cin >> cmd >> item; auto it = stock.find(item); int have = it != stock.end() ? it->second : 0; if (cmd == "add") { int k; std::cin >> k; stock[item] = have + k; } else if (cmd == "sell") { int k; std::cin >> k; if (have >= k) stock[item] = have - k; else std::cout << "fail\n"; } else { std::cout << have << '\n'; } } int inStock = 0; for (const auto& [item, count] : stock) if (count > 0) inStock++; std::cout << inStock << '\n';}
Cmain.c · 40 lines
#include <stdio.h>#include <string.h>/* C에는 사전이 없다: 물건 이름과 재고를 작은 표에 두고 처음부터 찾는다 */static char names[2000][13];static int counts[2000];static int size = 0;static int find_or_add(const char *item) { for (int i = 0; i < size; i++) if (strcmp(names[i], item) == 0) return i; strcpy(names[size], item); counts[size] = 0; return size++;}int main(void) { int m, k; char cmd[5], item[13]; scanf("%d", &m); for (int i = 0; i < m; i++) { scanf("%4s %12s", cmd, item); int at = find_or_add(item); if (strcmp(cmd, "add") == 0) { scanf("%d", &k); counts[at] += k; } else if (strcmp(cmd, "sell") == 0) { scanf("%d", &k); if (counts[at] >= k) counts[at] -= k; else puts("fail"); } else { printf("%d\n", counts[at]); } } int in_stock = 0; for (int i = 0; i < size; i++) if (counts[i] > 0) in_stock++; printf("%d\n", in_stock); return 0;}
Craykonmain.cray · 41 lines
m = Console.ReadLine().ToNumber();stock = Dict();for (i = 0; i < m; i++){ p = Console.ReadLine().Trim().Split(); item = p[1]; have = 0; if (stock.Contains(item)) { have = stock[item]; } if (p[0] == "add") { stock[item] = have + p[2].ToNumber(); } else if (p[0] == "sell") { k = p[2].ToNumber(); if (have >= k) { stock[item] = have - k; } else { Console.WriteLine("fail"); } } else { Console.WriteLine(have); }}inStock = 0;foreach (v in stock.Values){ if (v > 0) { inStock++; }}Console.WriteLine(inStock);