JavaScript 코딩테스트 - 큐

코딩 테스트 대비 저장용 포스트입니다.

BOJ 10845번: 큐 문제

"use strict";

class Node {
  constructor(value) {
    this.value = value;
    this.next = null;
  }
}

class Queue {
  constructor() {
    this.first = null;
    this.last = null;
    this.lenght = 0;
  }

  push(value) {
    const node = new Node(value);
    if (this.lenght === 0) {
      this.first = node;
      this.last = node;
    } else {
      this.last.next = node;
      this.last = node;
    }
    return ++this.lenght;
  }

  pop() {
    if (this.first === null) {
      return null;
    }
    if (this.first === this.last) {
      this.last = null;
    }
    const result = this.first.value;
    this.first = this.first.next;
    this.lenght--;
    return result;
  }
}

const fs = require("fs");
const input = fs.readFileSync("/dev/stdin").toString().split("\n");
const [N, ...orders] = input;
const q = new Queue();
let answer = "";

orders.forEach((order) => {
  if (order.startsWith("push")) {
    const [_, value] = order.split(" ");
    return q.push(value);
  }
  if (order === "front") {
    return (answer = q.lenght === 0 ? answer.concat("\n-1") : answer.concat(`\n${q.first.value}`));
  }
  if (order === "back") {
    return (answer = q.lenght === 0 ? answer.concat("\n-1") : answer.concat(`\n${q.last.value}`));
  }
  if (order === "size") {
    return (answer = answer.concat(`\n${q.lenght}`));
  }
  if (order === "empty") {
    return (answer = answer.concat(`\n${q.lenght === 0 ? 1 : 0}`));
  }
  if (order === "pop") {
    return (answer = q.lenght === 0 ? answer.concat("\n-1") : answer.concat(`\n${q.pop()}`));
  }
});

console.log(answer.slice(1)); // 맨 앞 공백 제거, trim() 써도 괜찮았을 듯..