結果

問題 No.1188 レベルX門松列
コンテスト
ユーザー EmKjp
提出日時 2020-08-22 14:05:11
言語 C#(csc)
(csc 3.9.0)
結果
AC  
実行時間 326 ms / 2,000 ms
コード長 9,335 bytes
コンパイル時間 3,846 ms
コンパイル使用メモリ 112,256 KB
実行使用メモリ 38,144 KB
最終ジャッジ日時 2024-10-15 08:21:41
合計ジャッジ時間 6,302 ms
ジャッジサーバーID
（参考情報） 		judge5 / judge2
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 21
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
Microsoft (R) Visual C# Compiler version 3.9.0-6.21124.20 (db94f4cc)
Copyright (C) Microsoft Corporation. All rights reserved.

ソースコード

diff # 

using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Text;
using System.Linq;

using E = System.Linq.Enumerable;
using System.Threading;
using System.Numerics;

internal partial class Solver {
    public void Run() {
        var n = ni();
        var a = ni(n);

        var ans1 = Solve(a);
        for (int i = 0; i < n; i++) {
            a[i] = -a[i];
        }
        var ans2 = Solve(a);
        cout.WriteLine(Math.Max(ans1, ans2));
    }

    private int Solve(int[] a) {
        var n = a.Length;
        var d = new IndexDictionary<int>(a);
        var segR = new SegmentTree<int>(Math.Max, int.MinValue);
        segR.Build(n + 1, i => 0);
        var dpR = new int[n];
        for (int i = n - 1; i >= 0; i--) {
            var index = d.IndexOf(a[i]);
            dpR[i] = (segR.Query(index + 1, n + 1) + 1);
            segR[index] = dpR[i];
        }

        var segL = new SegmentTree<int>(Math.Max, int.MinValue);
        segL.Build(n + 1, i => 0);
        var dpL = new int[n];
        for (int i = 0; i < n; i++) {
            var index = d.IndexOf(a[i]);
            dpL[i] = (segL.Query(index + 1, n + 1) + 1);
            segL[index] = dpL[i];
        }

        int ans = 0;
        for (int i = 0; i < n; i++) {
            ans = Math.Max(ans, Math.Min(dpL[i], dpR[i]) - 1);
        }
        /*a.TextDump();
        dpL.TextDump();
        dpR.TextDump();*/

        return ans;
    }
}

public sealed class SegmentTree<TMonoid> {
    public int Count { get; private set; }
    private TMonoid[] _node;
    private readonly TMonoid _identity;
    private readonly Func<TMonoid, TMonoid, TMonoid> _merge;

    public SegmentTree(Func<TMonoid, TMonoid, TMonoid> merge, TMonoid identity) {
        _merge = merge;
        _identity = identity;
    }

    public void Build(IList<TMonoid> array) {
        Build(array.Count, i => array[i]);
    }

    public void Build(int n, Func<int, TMonoid> create) {
        Count = n;

        _node = new TMonoid[2 * Count];

        for (int i = 0; i < n; i++) {
            _node[i + Count] = create(i);
        }

        for (int i = Count - 1; i > 0; i--) {
            _node[i] = _merge(_node[i << 1], _node[i << 1 | 1]);
        }
    }

    public void Set(int index, TMonoid val) {
        int p = index + Count;
        _node[p] = val;
        while (p > 0) {
            p >>= 1;
            _node[p] = _merge(_node[p << 1], _node[p << 1 | 1]);
        }
    }

    public TMonoid Query(int begin, int end) {
        TMonoid lv = _identity, rv = _identity;
        int l = begin + Count;
        int r = end + Count - 1;
        for (; l <= r; l >>= 1, r >>= 1) {
            if ((l & 1) == 1) { lv = _merge(lv, _node[l++]); }
            if ((r & 1) == 0) { rv = _merge(_node[r--], rv); }
        }
        return _merge(lv, rv);
    }

    public TMonoid this[int index] {
        get { return _node[index + Count]; }
        set { Set(index, value); }
    }
};
public class IndexDictionary<T> {
    private readonly Dictionary<T, int> _toIndex;
    private readonly T[] _array;

    public IndexDictionary(IEnumerable<T> source) : this(source, Comparer<T>.Default.Compare) { }

    public IndexDictionary(IEnumerable<T> source, Comparison<T> comparison) {
        _array = source.Distinct().ToArray();
        Array.Sort(_array, comparison);
        _toIndex = new Dictionary<T, int>(_array.Length);
        int index = -1;
        foreach (var x in _array) {
            _toIndex[x] = ++index;
        }
    }

    public int Count { get { return _array.Length; } }

    public T this[int index] { get { return _array[index]; } }

    public int IndexOf(T value) { return _toIndex[value]; }

    public T[] ToArray() {
        return _array.ToArray();
    }
}

// PREWRITEN CODE BEGINS FROM HERE

static public class StringExtensions {
    static public string JoinToString<T>(this IEnumerable<T> source, string separator = " ") {
        return string.Join(separator, source);
    }
}

internal partial class Solver : Scanner {
    static readonly int? StackSizeInMebiByte = null; //50;
    public static void StartAndJoin(Action action, int maxStackSize) {
        var thread = new Thread(new ThreadStart(action), maxStackSize);
        thread.Start();
        thread.Join();
    }

    public static void Main() {
#if LOCAL
        byte[] inputBuffer = new byte[1000000];
        var inputStream = Console.OpenStandardInput(inputBuffer.Length);
        using (var reader = new StreamReader(inputStream, Console.InputEncoding, false, inputBuffer.Length)) {
            Console.SetIn(reader);
            new Solver(Console.In, Console.Out).Run();
        }
#else
        Console.SetOut(new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
        if (StackSizeInMebiByte.HasValue) {
            StartAndJoin(() => new Solver(Console.In, Console.Out).Run(), StackSizeInMebiByte.Value * 1024 * 1024);
        } else {
            new Solver(Console.In, Console.Out).Run();
        }
        Console.Out.Flush();
#endif
    }

#pragma warning disable IDE0052
    private readonly TextReader cin;
    private readonly TextWriter cout;
    private readonly TextWriter cerr;
#pragma warning restore IDE0052

    public Solver(TextReader reader, TextWriter writer)
        : base(reader) {
        cin = reader;
        cout = writer;
        cerr = Console.Error;
    }

    public Solver(string input, TextWriter writer)
        : this(new StringReader(input), writer) {
    }

#pragma warning disable IDE1006
#pragma warning disable IDE0051
    private int ni() { return NextInt(); }
    private int[] ni(int n) { return NextIntArray(n); }
    private long nl() { return NextLong(); }
    private long[] nl(int n) { return NextLongArray(n); }
    private double nd() { return NextDouble(); }
    private double[] nd(int n) { return NextDoubleArray(n); }
    private string ns() { return Next(); }
    private string[] ns(int n) { return NextArray(n); }
#pragma warning restore IDE1006
#pragma warning restore IDE0051
}

#if DEBUG
internal static class LinqPadExtension {
    public static string TextDump<T>(this T obj) {
        if (obj is IEnumerable) return (obj as IEnumerable).Cast<object>().JoinToString().Dump();
        else return obj.ToString().Dump();
    }
    public static T Dump<T>(this T obj) {
        return LINQPad.Extensions.Dump(obj);
    }
}
#endif

public class Scanner {
    private readonly TextReader Reader;
    private readonly CultureInfo ci = CultureInfo.InvariantCulture;

    private readonly char[] buffer = new char[2 * 1024];
    private int cursor = 0, length = 0;
    private string Token;
    private readonly StringBuilder sb = new StringBuilder(1024);

    public Scanner()
        : this(Console.In) {
    }

    public Scanner(TextReader reader) {
        Reader = reader;
    }

    public int NextInt() { return checked((int)NextLong()); }
    public long NextLong() {
        var s = Next();
        long r = 0;
        int i = 0;
        bool negative = false;
        if (s[i] == '-') {
            negative = true;
            i++;
        }
        for (; i < s.Length; i++) {
            r = r * 10 + (s[i] - '0');
#if DEBUG
            if (!char.IsDigit(s[i])) throw new FormatException();
#endif
        }
        return negative ? -r : r;
    }
    public double NextDouble() { return double.Parse(Next(), ci); }
    public string[] NextArray(int size) {
        string[] array = new string[size];
        for (int i = 0; i < size; i++) {
            array[i] = Next();
        }

        return array;
    }
    public int[] NextIntArray(int size) {
        int[] array = new int[size];
        for (int i = 0; i < size; i++) {
            array[i] = NextInt();
        }

        return array;
    }

    public long[] NextLongArray(int size) {
        long[] array = new long[size];
        for (int i = 0; i < size; i++) {
            array[i] = NextLong();
        }

        return array;
    }

    public double[] NextDoubleArray(int size) {
        double[] array = new double[size];
        for (int i = 0; i < size; i++) {
            array[i] = NextDouble();
        }

        return array;
    }

    public string Next() {
        if (Token == null) {
            if (!StockToken()) {
                throw new Exception();
            }
        }
        var token = Token;
        Token = null;
        return token;
    }

    public bool HasNext() {
        if (Token != null) {
            return true;
        }

        return StockToken();
    }

    private bool StockToken() {
        while (true) {
            sb.Clear();
            while (true) {
                if (cursor >= length) {
                    cursor = 0;
                    if ((length = Reader.Read(buffer, 0, buffer.Length)) <= 0) {
                        break;
                    }
                }
                var c = buffer[cursor++];
                if (33 <= c && c <= 126) {
                    sb.Append(c);
                } else {
                    if (sb.Length > 0) break;
                }
            }

            if (sb.Length > 0) {
                Token = sb.ToString();
                return true;
            }

            return false;
        }
    }
}
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