結果

問題 No.5017 Tool-assisted Shooting
ユーザー KumaTachiRenKumaTachiRen
提出日時 2023-07-16 18:05:32
言語 C#
(.NET 8.0.203)
結果
AC  
実行時間 1,085 ms / 2,000 ms
コード長 20,000 bytes
コンパイル時間 9,777 ms
コンパイル使用メモリ 145,168 KB
実行使用メモリ 66,864 KB
スコア 2,447,455
平均クエリ数 1213.38
最終ジャッジ日時 2023-07-16 18:07:29
合計ジャッジ時間 113,790 ms
ジャッジサーバーID
（参考情報） 		judge16 / judge14
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テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 1,058 ms
57,760 KB
testcase_01 AC 1,034 ms
59,436 KB
testcase_02 AC 1,007 ms
60,888 KB
testcase_03 AC 971 ms
59,036 KB
testcase_04 AC 1,009 ms
58,472 KB
testcase_05 AC 947 ms
61,368 KB
testcase_06 AC 1,042 ms
58,804 KB
testcase_07 AC 853 ms
66,864 KB
testcase_08 AC 1,022 ms
59,628 KB
testcase_09 AC 882 ms
61,892 KB
testcase_10 AC 1,012 ms
58,136 KB
testcase_11 AC 1,038 ms
59,724 KB
testcase_12 AC 1,026 ms
55,884 KB
testcase_13 AC 1,010 ms
59,292 KB
testcase_14 AC 1,002 ms
57,772 KB
testcase_15 AC 1,027 ms
59,708 KB
testcase_16 AC 1,034 ms
55,728 KB
testcase_17 AC 974 ms
58,568 KB
testcase_18 AC 987 ms
58,480 KB
testcase_19 AC 932 ms
62,108 KB
testcase_20 AC 1,050 ms
57,792 KB
testcase_21 AC 1,026 ms
57,352 KB
testcase_22 AC 1,045 ms
55,652 KB
testcase_23 AC 947 ms
61,736 KB
testcase_24 AC 1,085 ms
59,960 KB
testcase_25 AC 966 ms
61,012 KB
testcase_26 AC 894 ms
60,548 KB
testcase_27 AC 1,028 ms
60,772 KB
testcase_28 AC 997 ms
58,048 KB
testcase_29 AC 1,016 ms
56,460 KB
testcase_30 AC 1,034 ms
60,112 KB
testcase_31 AC 1,057 ms
58,172 KB
testcase_32 AC 1,028 ms
59,948 KB
testcase_33 AC 1,005 ms
58,536 KB
testcase_34 AC 998 ms
60,848 KB
testcase_35 AC 1,037 ms
59,196 KB
testcase_36 AC 944 ms
60,932 KB
testcase_37 AC 937 ms
61,588 KB
testcase_38 AC 1,011 ms
61,672 KB
testcase_39 AC 1,058 ms
58,152 KB
testcase_40 AC 901 ms
64,420 KB
testcase_41 AC 895 ms
64,700 KB
testcase_42 AC 1,048 ms
56,896 KB
testcase_43 AC 1,030 ms
58,124 KB
testcase_44 AC 995 ms
62,272 KB
testcase_45 AC 893 ms
58,976 KB
testcase_46 AC 1,028 ms
58,552 KB
testcase_47 AC 934 ms
59,748 KB
testcase_48 AC 1,010 ms
57,020 KB
testcase_49 AC 1,023 ms
58,756 KB
testcase_50 AC 927 ms
62,884 KB
testcase_51 AC 1,026 ms
61,808 KB
testcase_52 AC 1,014 ms
58,756 KB
testcase_53 AC 997 ms
56,740 KB
testcase_54 AC 978 ms
60,152 KB
testcase_55 AC 1,052 ms
59,544 KB
testcase_56 AC 1,006 ms
58,736 KB
testcase_57 AC 1,047 ms
59,836 KB
testcase_58 AC 922 ms
61,932 KB
testcase_59 AC 1,066 ms
59,604 KB
testcase_60 AC 1,005 ms
61,076 KB
testcase_61 AC 923 ms
60,392 KB
testcase_62 AC 993 ms
57,620 KB
testcase_63 AC 1,028 ms
59,048 KB
testcase_64 AC 1,061 ms
58,340 KB
testcase_65 AC 927 ms
62,404 KB
testcase_66 AC 983 ms
59,696 KB
testcase_67 AC 1,036 ms
56,620 KB
testcase_68 AC 935 ms
62,392 KB
testcase_69 AC 999 ms
60,156 KB
testcase_70 AC 1,045 ms
59,236 KB
testcase_71 AC 1,012 ms
58,340 KB
testcase_72 AC 965 ms
59,512 KB
testcase_73 AC 1,031 ms
58,452 KB
testcase_74 AC 1,024 ms
56,848 KB
testcase_75 AC 1,024 ms
62,228 KB
testcase_76 AC 990 ms
58,996 KB
testcase_77 AC 1,010 ms
61,096 KB
testcase_78 AC 954 ms
61,652 KB
testcase_79 AC 971 ms
58,272 KB
testcase_80 AC 944 ms
62,492 KB
testcase_81 AC 989 ms
61,192 KB
testcase_82 AC 988 ms
62,140 KB
testcase_83 AC 929 ms
61,132 KB
testcase_84 AC 1,013 ms
60,584 KB
testcase_85 AC 1,026 ms
60,172 KB
testcase_86 AC 1,027 ms
58,236 KB
testcase_87 AC 1,030 ms
57,532 KB
testcase_88 AC 993 ms
59,556 KB
testcase_89 AC 1,054 ms
58,308 KB
testcase_90 AC 1,052 ms
62,164 KB
testcase_91 AC 1,036 ms
57,592 KB
testcase_92 AC 968 ms
56,988 KB
testcase_93 AC 1,034 ms
59,280 KB
testcase_94 AC 943 ms
58,956 KB
testcase_95 AC 1,038 ms
60,080 KB
testcase_96 AC 1,014 ms
58,660 KB
testcase_97 AC 951 ms
59,976 KB
testcase_98 AC 891 ms
64,236 KB
testcase_99 AC 931 ms
61,740 KB
権限があれば一括ダウンロードができます
コンパイルメッセージ
  Determining projects to restore...
  Restored /home/judge/data/code/main.csproj (in 154 ms).
.NET 向け Microsoft (R) Build Engine バージョン 17.0.0-preview-21470-01+cb055d28f
Copyright (C) Microsoft Corporation.All rights reserved.

  プレビュー版の .NET を使用しています。https://aka.ms/dotnet-core-preview をご覧ください
  main -> /home/judge/data/code/bin/Release/net6.0/main.dll
  main -> /home/judge/data/code/bin/Release/net6.0/publish/

ソースコード

diff # 

using System;
using System.ComponentModel;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Diagnostics.Contracts;
using System.IO;
using System.Linq;
using System.Numerics;
using System.Runtime.Intrinsics.X86;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Text;
using static Functions;
using static OutputLib;

static class Program
{
    static public void Main(string[] args)
    {
        Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
        new Solver();
        Console.Out.Flush();
    }
}

public class Solver
{
    public Solver()
    {
        Solve();
    }

    const int width = 25;
    const int height = 60;
    const int max_turn = 1000;

    void Solve()
    {
        var enemy = new (long health, long power, long point)[width, height];
        for (int i = 0; i < width; i++)
            for (int j = 0; j < height; j++)
                enemy[i, j] = (0, 0, 0);

        int player_pos = 12;
        long score = 0;
        long power_sum = 0;

        var move_deque = new Deque<int>();
        var pow3 = new long[40];
        pow3[0] = 1;
        for (int i = 0; i + 1 < pow3.Length; i++) pow3[i + 1] = pow3[i] * 3;
        var history = new Stack<(int x, int y, (long, long, long))>();

        (long score, long power) SafeAttack(int x, int y, long lvl)
        {
            history.Push((x, y, enemy[x, y]));
            var (h, p, pt) = enemy[x, y];
            long r1 = 0, r2 = 0;
            if (h <= lvl)
            {
                r1 = pt;
                r2 = p;
                h = 0;
                p = 0;
                pt = 0;
            }
            else
            {
                h -= lvl;
            }
            enemy[x, y] = (h, p, pt);
            return (r1, r2);
        }
        void SafeAttackUndo()
        {
            if (history.Count > 0)
            {
                var (u, v, p) = history.Pop();
                enemy[u, v] = p;
            }
        }
        void SafeAttackReset()
        {
            while (history.Count > 0)
            {
                var (u, v, p) = history.Pop();
                enemy[u, v] = p;
            }
        }

        int turn = 0;
        for (; turn < max_turn; turn++)
        {

            long level = 1 + power_sum / 100;

            for (int i = 0; i < width; i++)
            {
                for (int j = 0; j + 1 < height; j++)
                    enemy[i, j] = enemy[i, j + 1];
                enemy[i, height - 1] = (0, 0, 0);
            }

            {
                int n = ri;
                if (n == -1) break;

                for (int i = 0; i < n; i++)
                {
                    int h = ri, p = ri, x = ri;
                    enemy[x, height - 1] = (h, p, h);
                }
            }

            {
                if (move_deque.Count == 0)
                {

                    const int period = 15, div = 5;
                    const int beam_size = 20;
                    const long score_scale = 10;

                    var best_list = new List<(long s, long score)>() { (0, 0) };
                    long prod = 1;
                    for (int time = 0; time < period; time += div)
                    {
                        var next_list = new List<(long s, long score)>();
                        foreach (var (s, bscore) in best_list)
                        {
                            int x = player_pos;
                            long sc = 0, pw = power_sum;
                            for (int t = 0; t < time; t++)
                            {
                                int d = (int)((s / pow3[t]) % 3 - 1);

                                sc -= Math.Abs(d);

                                x = SafeMod(x + d, width);
                                int z = t;
                                while (z < height && enemy[x, z].health == 0) z++;
                                if (z < height)
                                {
                                    var res = SafeAttack(x, z, 1 + pw / 100);
                                    sc += res.score * score_scale;
                                    pw += res.power;
                                }
                            }
                            for (int ns = 0; ns < pow3[div]; ns++)
                            {
                                int y = x;
                                long nsc = sc, npw = power_sum;
                                int attackcnt = 0;
                                bool ok = true;
                                for (int t = 0; t < div; t++)
                                {
                                    int d = (int)((ns / pow3[t]) % 3 - 1);

                                    nsc -= Math.Abs(d);

                                    y = SafeMod(y + d, width);
                                    if (enemy[y, time + t].health > 0)
                                    {
                                        ok = false;
                                        break;
                                    }
                                    int z = time + t;
                                    while (z < height && enemy[y, z].health == 0) z++;
                                    if (z < height)
                                    {
                                        var res = SafeAttack(y, z, 1 + npw / 100);
                                        attackcnt++;
                                        nsc += res.score * score_scale;
                                        npw += res.power;
                                    }
                                    if (enemy[y, time + t + 1].health > 0)
                                    {
                                        ok = false;
                                        break;
                                    }
                                }
                                for (int i = 0; i < attackcnt; i++) SafeAttackUndo();
                                if (ok) next_list.Add((s + prod * ns, nsc));
                            }
                            SafeAttackReset();
                        }

                        best_list = new List<(long s, long score)>();
                        next_list.Sort((p1, p2) => -Sign(p1.score - p2.score));
                        for (int i = 0; i < next_list.Count && i < beam_size; i++)
                            best_list.Add(next_list[i]);

                        prod *= pow3[div];
                    }

                    if (best_list.Count > 0)
                    {
                        long best = best_list[0].s;
                        for (int t = 0; t < 10; t++)
                        {
                            int d = (int)((best / pow3[t]) % 3 - 1);
                            move_deque.PushBack(d);
                        }
                    }
                }

                int move = 0;
                if (move_deque.Count > 0) move = move_deque.PopFront();
                else Write("# :(");

                {
                    int next_pos = SafeMod(player_pos + move, width);
                    if (enemy[next_pos, 0].health > 0 || enemy[next_pos, 1].health > level)
                    {
                        for (int d = -1; d <= 1; d++)
                        {
                            int y = SafeMod(player_pos + d, width);
                            if (enemy[y, 0].health == 0 && enemy[y, 1].health <= level)
                            {
                                move = d;
                                Write($"# dodge time: {turn} pos: {player_pos} -> {y}");
                                break;
                            }
                        }
                    }
                }

                if (move == -1) WriteFlush("L");
                if (move == 0) WriteFlush("S");
                if (move == 1) WriteFlush("R");
                player_pos = SafeMod(player_pos + move, width);
            }

            if (enemy[player_pos, 0].health > 0)
            {
                Write($"# crash time: {turn} pos: {player_pos}");
                break;
            }

            for (int i = 0; i < height; i++)
            {
                if (enemy[player_pos, i].health > 0)
                {
                    var (h, p, pt) = enemy[player_pos, i];
                    if (h <= level)
                    {
                        power_sum += p;
                        score += pt;
                        Write($"# defeat time: {turn} pos: {player_pos} point: {pt} score: {score}");
                        h = 0;
                        p = 0;
                        pt = 0;
                    }
                    else
                    {
                        h -= level;
                    }
                    enemy[player_pos, i] = (h, p, pt);
                    break;
                }
            }
        }
        WriteError($"Turn: {turn}, Score: {score}");
    }

    const long INF = 1L << 60;
    int ri { [MethodImpl(256)] get => (int)sc.Integer(); }
    long rl { [MethodImpl(256)] get => sc.Integer(); }
    uint rui { [MethodImpl(256)] get => (uint)sc.UInteger(); }
    ulong rul { [MethodImpl(256)] get => sc.UInteger(); }
    double rd { [MethodImpl(256)] get => sc.Double(); }
    string rs { [MethodImpl(256)] get => sc.Scan(); }
    string rline { [MethodImpl(256)] get => sc.Line(); }
    public StreamScanner sc = new StreamScanner(Console.OpenStandardInput());
}

public static class Functions
{
    [MethodImpl(256)]
    public static int Popcount(ulong x)
    {
        x = (x & 0x5555555555555555UL) + ((x >> 1) & 0x5555555555555555UL);
        x = (x & 0x3333333333333333UL) + ((x >> 2) & 0x3333333333333333UL);
        x = (x & 0x0f0f0f0f0f0f0f0fUL) + ((x >> 4) & 0x0f0f0f0f0f0f0f0fUL);
        x = (x & 0x00ff00ff00ff00ffUL) + ((x >> 8) & 0x00ff00ff00ff00ffUL);
        x = (x & 0x0000ffff0000ffffUL) + ((x >> 16) & 0x0000ffff0000ffffUL);
        x = (x & 0x00000000ffffffffUL) + ((x >> 32) & 0x00000000ffffffffUL);
        return (int)x;
    }
    [MethodImpl(256)]
    public static int Popcount(int x)
    {
        x = (x & 0x55555555) + ((x >> 1) & 0x55555555);
        x = (x & 0x33333333) + ((x >> 2) & 0x33333333);
        x = (x & 0x0f0f0f0f) + ((x >> 4) & 0x0f0f0f0f);
        x = (x & 0x00ff00ff) + ((x >> 8) & 0x00ff00ff);
        x = (x & 0x0000ffff) + ((x >> 16) & 0x0000ffff);
        return x;
    }
    [MethodImpl(256)]
    public static int Ctz(long x)
    {
        if (x == 0) return -1;
        return Popcount((ulong)((x & -x) - 1));
    }
    [MethodImpl(256)]
    public static int CeilPow2(int n)
    {
        int x = 0;
        while ((1 << x) < n) x++;
        return x;
    }
    [MethodImpl(256)]
    public static int SafeMod(int x, int m)
    {
        int r = x % m;
        return r < 0 ? r + Math.Abs(m) : r;
    }
    [MethodImpl(256)]
    public static long SafeMod(long x, long m)
    {
        long r = x % m;
        return r < 0 ? r + Math.Abs(m) : r;
    }
    [MethodImpl(256)] public static int Sign(long x) => x == 0 ? 0 : (x < 0 ? -1 : 1);
    [MethodImpl(256)] public static int Sign(double x) => x == 0 ? 0 : (x < 0 ? -1 : 1);
    [MethodImpl(256)] public static int DigitSum(long n, int d = 10) { long s = 0; while (n > 0) { s += n % d; n /= d; } return (int)s; }
    [MethodImpl(256)] public static long Floor(long a, long b) => a >= 0 ? a / b : (a + 1) / b - 1;
    [MethodImpl(256)] public static long Ceil(long a, long b) => a > 0 ? (a - 1) / b + 1 : a / b;
    [MethodImpl(256)] public static int Gcd(int a, int b) => b == 0 ? a : Gcd(b, a % b);
    [MethodImpl(256)] public static long Gcd(long a, long b) => b == 0 ? a : Gcd(b, a % b);
    [MethodImpl(256)] public static void Swap(ref int x, ref int y) { x ^= y; y ^= x; x ^= y; }
    [MethodImpl(256)] public static void Swap(ref long x, ref long y) { x ^= y; y ^= x; x ^= y; }
    [MethodImpl(256)] public static void Swap<T>(ref T x, ref T y) { T t = y; y = x; x = t; }
    [MethodImpl(256)] public static T Clamp<T>(T x, T l, T r) where T : IComparable<T> => x.CompareTo(l) <= 0 ? l : (x.CompareTo(r) <= 0 ? x : r);
    [MethodImpl(256)] public static T Clamp<T>(ref T x, T l, T r) where T : IComparable<T> => x = x.CompareTo(l) <= 0 ? l : (x.CompareTo(r) <= 0 ? x : r);
    [MethodImpl(256)] public static void Chmin<T>(ref T x, T y) where T : IComparable<T> { if (x.CompareTo(y) > 0) x = y; }
    [MethodImpl(256)] public static void Chmax<T>(ref T x, T y) where T : IComparable<T> { if (x.CompareTo(y) < 0) x = y; }
    public static int LowerBound(long[] arr, long val, int l = -1, int r = -1) => LowerBound<long>(arr.AsSpan(), t => Sign(t - val), l, r);
    public static int LowerBound(int[] arr, int val, int l = -1, int r = -1) => LowerBound<int>(arr.AsSpan(), t => t - val, l, r);
    public static int LowerBound<T>(T[] arr, Func<T, int> comp, int l = -1, int r = -1) => LowerBound<T>(arr.AsSpan<T>(), comp, l, r);
    public static int LowerBound<T>(Span<T> data, Func<T, int> comp, int l = -1, int r = -1)
    {
        if (data.Length == 0) return -1;
        if (l == -1) l = 0;
        if (r == -1) r = data.Length;
        while (l < r)
        {
            int x = (l + r) / 2;
            if (comp(data[x]) < 0) l = x + 1;
            else r = x;
        }
        return l;
    }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static string ToBase2(long v, int digit = -1)
    {
        if (digit == -1)
        {
            digit = 0;
            while ((v >> digit) > 0) digit++;
        }
        var c = new string[digit];
        for (int i = 0; i < digit; i++) c[digit - 1 - i] = ((v >> i) & 1) == 0 ? "0" : "1";
        return string.Join("", c);
    }
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static string ToBaseN(long v, int n, int digit = -1)
    {
        if (digit == -1)
        {
            digit = 0;
            long pow = 1;
            while (v >= pow) { digit++; pow *= n; }
        }
        var c = new int[digit];
        for (int i = 0; i < digit; i++, v /= n) c[digit - 1 - i] = (int)(v % n);
        return string.Join("", c);
    }
}

public class StreamScanner
{
    public StreamScanner(Stream stream) { str = stream; }
    private readonly Stream str;
    private readonly byte[] buf = new byte[1024];
    private int len, ptr;
    public bool isEof = false;
    public bool IsEndOfStream { get { return isEof; } }
    [MethodImpl(256)]
    private byte read()
    {
        if (isEof) throw new EndOfStreamException();
        if (ptr >= len)
        {
            ptr = 0;
            if ((len = str.Read(buf, 0, 1024)) <= 0) { isEof = true; return 0; }
        }
        return buf[ptr++];
    }
    [MethodImpl(256)]
    public char Char()
    {
        byte b = 0;
        do b = read();
        while (b < 33 || 126 < b);
        return (char)b;
    }
    [MethodImpl(256)]
    public string Line()
    {
        var sb = new StringBuilder();
        for (var b = Char(); b != 10 && !isEof; b = (char)read()) sb.Append(b);
        return sb.ToString();
    }
    [MethodImpl(256)]
    public string Scan()
    {
        var sb = new StringBuilder();
        for (var b = Char(); b >= 33 && b <= 126; b = (char)read()) sb.Append(b);
        return sb.ToString();
    }
    [MethodImpl(256)]
    public long Integer()
    {
        long ret = 0; byte b = 0; var ng = false;
        do b = read();
        while (b != '-' && (b < '0' || '9' < b));
        if (b == '-') { ng = true; b = read(); }
        for (; true; b = read())
        {
            if (b < '0' || '9' < b) return ng ? -ret : ret;
            else ret = ret * 10 + b - '0';
        }
    }
    [MethodImpl(256)]
    public ulong UInteger()
    {
        ulong ret = 0; byte b = 0;
        do b = read();
        while (b < '0' || '9' < b);
        for (; true; b = read())
        {
            if (b < '0' || '9' < b) return ret;
            else ret = ret * 10 + b - '0';
        }
    }
    [MethodImpl(256)]
    public double Double() => double.Parse(Scan());
}

public static class OutputLib
{
    [MethodImpl(256)] public static void WriteJoin<T>(string s, IEnumerable<T> t) => Console.WriteLine(string.Join(s, t));
    [MethodImpl(256)]
    public static void WriteMat<T>(T[,] a)
    {
        int sz1 = a.GetLength(0);
        int sz2 = a.GetLength(1);
        for (int i = 0; i < sz1; i++)
        {
            var b = new T[sz2];
            for (int j = 0; j < sz2; j++) b[j] = a[i, j];
            WriteJoin(" ", b);
        }
    }
    [MethodImpl(256)] public static void WriteMat<T>(T[][] a) { for (int i = 0; i < a.Length; i++) WriteJoin(" ", a[i]); }
    [MethodImpl(256)] public static void Write(object t) => Console.WriteLine(t.ToString());
    [MethodImpl(256)] public static void Write(string str) => Console.WriteLine(str);
    [MethodImpl(256)] public static void Write(string str, object arg1) => Console.WriteLine(str, arg1);
    [MethodImpl(256)] public static void Write(string str, object arg1, object arg2) => Console.WriteLine(str, arg1, arg2);
    [MethodImpl(256)] public static void Write(string str, object arg1, object arg2, object arg3) => Console.WriteLine(str, arg1, arg2, arg3);
    [MethodImpl(256)] public static void Write(string str, params object[] arg) => Console.WriteLine(str, arg);
    [MethodImpl(256)] public static void WriteFlush(object t) { Console.WriteLine(t.ToString()); Console.Out.Flush(); }
    [MethodImpl(256)] public static void WriteError(object t) => Console.Error.WriteLine(t.ToString());
    [MethodImpl(256)] public static void Flush() => Console.Out.Flush();
    [MethodImpl(256)] public static void YN(bool t) => Console.WriteLine(t ? "YES" : "NO");
    [MethodImpl(256)] public static void Yn(bool t) => Console.WriteLine(t ? "Yes" : "No");
    [MethodImpl(256)] public static void yn(bool t) => Console.WriteLine(t ? "yes" : "no");
}

public class Deque<T>
{
    class Node
    {
        public Node Prev, Next;
        public T Value;
        public Node(T v)
        {
            Value = v;
            Prev = null;
            Next = null;
        }
    }
    public int Count { get; private set; }
    Node Front, Back;
    public Deque() { }
    [MethodImpl(256)]
    public void PushBack(T v)
    {
        Node x = new Node(v);
        if (Count == 0)
        {
            Front = x;
            Back = x;
        }
        else
        {
            Back.Next = x;
            x.Prev = Back;
            Back = x;
        }
        Count++;
    }
    [MethodImpl(256)]
    public void PushFront(T v)
    {
        Node x = new Node(v);
        if (Count == 0)
        {
            Front = x;
            Back = x;
        }
        else
        {
            Front.Prev = x;
            x.Next = Front;
            Front = x;
        }
        Count++;
    }
    [MethodImpl(256)]
    public T PopBack()
    {
        if (Count == 0) throw new InvalidOperationException("Deque empty.");
        T v = Back.Value;
        Count--;
        if (Count == 0)
        {
            Front = null;
            Back = null;
        }
        else
        {
            Back = Back.Prev;
        }
        return v;
    }
    [MethodImpl(256)]
    public T PopFront()
    {
        if (Count == 0) throw new InvalidOperationException("Deque empty.");
        T v = Front.Value;
        Count--;
        if (Count == 0)
        {
            Front = null;
            Back = null;
        }
        else
        {
            Front = Front.Next;
        }
        return v;
    }
    [MethodImpl(256)]
    public T PeekBack()
    {
        if (Count == 0) throw new InvalidOperationException("Deque empty.");
        return Back.Value;
    }
    [MethodImpl(256)]
    public T PeekFront()
    {
        if (Count == 0) throw new InvalidOperationException("Deque empty.");
        return Front.Value;
    }
}
0