题解 | #【模板】队列#

using System.Collections.Generic;
using System;
public class Program {
    public static void Main() {
        Queue q = new Queue(); 
        //读取操作个数
        int n = int.Parse(Console.ReadLine());
        while (n-- >0 ) { 
            string opr = Console.ReadLine();
            if(opr.IndexOf("push")!=-1){
                q.Enqueue(int.Parse(opr.Split(" ")[1]));
            }else if(opr.Equals("pop")){
                q.Dequeue();
            }else{
                q.Peek();
            }
        }
    }

    public class Queue{
        List<int> list = new List<int>();
        public void Enqueue(int val){
            list.Add(val);
        }

        public void Dequeue(){
            if(list.Count == 0)
            {
                Console.WriteLine("error");
                return;
            }
            Console.WriteLine(list[0]);
            list.RemoveAt(0);        
        }

        public void Peek(){
            if(list.Count == 0)
            {
                Console.WriteLine("error");
                return;
            }
            Console.WriteLine(list[0]);
        }
    }
}