学内プロコン(15/03/19)

client.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Net;

class Client
{
    readonly string Token = "unique_token";
    readonly bool IsReadFromConsole;
    private WebClient Web { get; set; }
    private StringReader Stream { get; set; }

    public Client()
    {
        this.IsReadFromConsole = true;
    }

    public Client(string problemUri)
    {
        this.Web = new WebClient();
        // initial download
        Web.DownloadData("http://foo.com/barbar.png");
        this.Stream = new StringReader(Web.DownloadString(problemUri)); // break at here. then continue.
        this.IsReadFromConsole = false;
    }


    public string ReadLine()
    {
        if (IsReadFromConsole) return Console.ReadLine();
        else return Stream.ReadLine();
    }

    public void Send(string dest, string name, string value)
    {
        var values = new System.Collections.Specialized.NameValueCollection();
        values.Add("token", Token);
        values.Add(name, value);
        Web.UploadValues(dest, values);
    }
}

procon.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

class Program
{
    // ref: https://github.com/OCTPC/miniprocon/blob/master/miniprocon001/regulation.md
    static void Main(string[] args)
    {
        var client = new Client("http://localhost/problem"); // 入出力
        string[] str = client.ReadLine().Split(' ');
        long x = long.Parse(str[0]);
        long y = long.Parse(str[1]);

        // 絶対値
        long xx = x < 0 ? -x : x;
        long yy = y < 0 ? -y : y;

        var primes = Primes(xx > yy ? xx : yy).ToList();

        string ans = "";
        // x
        if (x < 0)
        {
            ans += string.Join("\n", Calc(x, primes).Select(p => (p < 0 ? "R" : "L") + (p < 0 ? -p : p)));
        }
        else
        {
            ans += string.Join("\n", Calc(x, primes).Select(p => (p < 0 ? "L" : "R") + (p < 0 ? -p : p)));
        }
        ans += "\n";
        // y
        if (y < 0)
        {
            ans += string.Join("\n", Calc(y, primes).Select(p => (p < 0 ? "U" : "D") + (p < 0 ? -p : p)));
        }
        else
        {
            ans += string.Join("\n", Calc(y, primes).Select(p => (p < 0 ? "D" : "U") + (p < 0 ? -p : p)));
        }

        client.Send("http://localhost/post", "answer", ans);
        Console.WriteLine(ans);
    }

    // 1方向の解の計算
    static IEnumerable<long> Calc(long dest, List<long> primes)
    {
        // 絶対値
        dest = dest < 0 ? -dest : dest;
        // 一発で決まるとき
        if (primes.Contains(dest))
        {
            yield return dest;
            yield break;
        }

        // あきらめて前方から詰めていく
        long remaining = dest;
        while (remaining > 1)
        {
            // 貪欲に埋める
            long value = primes.TakeWhile(p => p <= remaining).Last();
            remaining -= value;
            yield return value;
        }

        if (remaining == 0)
        {
            // ぴったり。めでたしめでたし。
            yield break;
        }
        else
        {
            while (remaining != 0)
            {
                // 1ずつ進めるんじゃ
                yield return 3;
                yield return -2;
                remaining -= 1;
            }
        }
    }

    // エラトステネスの篩
    static IEnumerable<long> Primes(long max)
    {
        if (max < 2) yield break;
        long sqrt = (long)Math.Sqrt(max);
        var arr = new bool[max + 1]; // not prime?
        for (long i = 2; i <= sqrt; i++)
        {
            if (arr[i]) continue;
            for (long j = i + i; j < arr.Length; j += i)
                arr[j] = true;
        }

        for (long i = 2; i < arr.Length; i++)
            if (!arr[i]) yield return i;
    }
}