結果

問題 No.271 next_permutation (2)
ユーザー 紙ぺーぱー
提出日時 2016-06-04 20:33:58
言語 C#(csc)
(csc 3.9.0)
結果
AC  
実行時間 174 ms / 2,000 ms
コード長 9,555 bytes
コンパイル時間 2,466 ms
コンパイル使用メモリ 120,476 KB
実行使用メモリ 31,380 KB
最終ジャッジ日時 2024-11-26 07:46:03
合計ジャッジ時間 3,335 ms
ジャッジサーバーID
（参考情報） 		judge1 / 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
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 #
プレゼンテーションモードにする

using System;
using System.Linq;
using System.Linq.Expressions;
using System.Collections.Generic;
using Debug = System.Diagnostics.Debug;
using StringBuilder = System.Text.StringBuilder;
using System.Numerics;
using Point = System.Numerics.Complex;
using Number = System.Int64;
namespace Program
{
    public class Solver
    {
        public void Solve()
        {
            var n = sc.Integer();
            var k = sc.Long();
            var a = sc.Integer(n);
            var P = new FactorialNumber(a);
            Debug.WriteLine(P);
            var i1 = P.GetInversion();
            var m = P.Add(k);
            var i2 = P.GetInversion();
            Debug.WriteLine(P);
            IO.Printer.Out.WriteLine(m * FactorialNumber.fact[n] * n * (n - 1) * ModInteger.Inverse(4) + i2 - i1);
        }
        public IO.StreamScanner sc = new IO.StreamScanner(Console.OpenStandardInput());
        static T[] Enumerate<T>(int n, Func<int, T> f) { var a = new T[n]; for (int i = 0; i < n; ++i) a[i] = f(i); return a; }
        static public void Swap<T>(ref T a, ref T b) { var tmp = a; a = b; b = tmp; }
    }
}
#region main
static class Ex
{
    static public string AsString(this IEnumerable<char> ie) { return new string(System.Linq.Enumerable.ToArray(ie)); }
    static public string AsJoinedString<T>(this IEnumerable<T> ie, string st = " ") { return string.Join(st, ie); }
    static public void Main()
    {
        var solver = new Program.Solver();
        solver.Solve();
        Program.IO.Printer.Out.Flush();
    }
}
#endregion
#region Ex
namespace Program.IO
{
    using System.IO;
    using System.Text;
    using System.Globalization;
    public class Printer : StreamWriter
    {
        static Printer() { Out = new Printer(Console.OpenStandardOutput()) { AutoFlush = false }; }
        public static Printer Out { get; set; }
        public override IFormatProvider FormatProvider { get { return CultureInfo.InvariantCulture; } }
        public Printer(System.IO.Stream stream) : base(stream, new UTF8Encoding(false, true)) { }
        public Printer(System.IO.Stream stream, Encoding encoding) : base(stream, encoding) { }
        public void Write<T>(string format, T[] source) { base.Write(format, source.OfType<object>().ToArray()); }
        public void WriteLine<T>(string format, T[] source) { base.WriteLine(format, source.OfType<object>().ToArray()); }
    }
    public class StreamScanner
    {
        public StreamScanner(Stream stream) { str = stream; }
        public readonly Stream str;
        private readonly byte[] buf = new byte[1024];
        private int len, ptr;
        public bool isEof = false;
        public bool IsEndOfStream { get { return isEof; } }
        private byte read()
        {
            if (isEof) return 0;
            if (ptr >= len) { ptr = 0; if ((len = str.Read(buf, 0, 1024)) <= 0) { isEof = true; return 0; } }
            return buf[ptr++];
        }
        public char Char() { byte b = 0; do b = read(); while ((b < 33 || 126 < b) && !isEof); return (char)b; }
        public string Scan()
        {
            var sb = new StringBuilder();
            for (var b = Char(); b >= 33 && b <= 126; b = (char)read())
                sb.Append(b);
            return sb.ToString();
        }
        public string ScanLine()
        {
            var sb = new StringBuilder();
            for (var b = Char(); b != '\n'; b = (char)read())
                if (b == 0) break;
                else if (b != '\r') sb.Append(b);
            return sb.ToString();
        }
        public long Long()
        {
            if (isEof) return long.MinValue;
            long ret = 0; byte b = 0; var ng = false;
            do b = read();
            while (b != 0 && b != '-' && (b < '0' || '9' < b));
            if (b == 0) return long.MinValue;
            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';
            }
        }
        public int Integer() { return (isEof) ? int.MinValue : (int)Long(); }
        public double Double() { var s = Scan(); return s != "" ? double.Parse(s, CultureInfo.InvariantCulture) : double.NaN; }
        private T[] enumerate<T>(int n, Func<T> f)
        {
            var a = new T[n];
            for (int i = 0; i < n; ++i) a[i] = f();
            return a;
        }
        public char[] Char(int n) { return enumerate(n, Char); }
        public string[] Scan(int n) { return enumerate(n, Scan); }
        public double[] Double(int n) { return enumerate(n, Double); }
        public int[] Integer(int n) { return enumerate(n, Integer); }
        public long[] Long(int n) { return enumerate(n, Long); }
    }
}
#endregion
#region ModNumber
public partial struct ModInteger
{
    public const long Mod = (long)1e9 + 7;
    public long num;
    public ModInteger(long n) : this() { num = n % Mod; if (num < 0) num += Mod; }
    public override string ToString() { return num.ToString(); }
    public static ModInteger operator +(ModInteger l, ModInteger r) { var n = l.num + r.num; if (n >= Mod) n -= Mod; return new ModInteger() { num = 
        n }; }
    public static ModInteger operator -(ModInteger l, ModInteger r) { var n = l.num + Mod - r.num; if (n >= Mod) n -= Mod; return new ModInteger() { 
        num = n }; }
    public static ModInteger operator *(ModInteger l, ModInteger r) { return new ModInteger(l.num * r.num); }
    public static ModInteger operator ^(ModInteger l, long r) { return ModInteger.Pow(l, r); }
    public static implicit operator ModInteger(long n) { return new ModInteger(n); }
    public static ModInteger Pow(ModInteger v, long k)
    {
        ModInteger ret = 1;
        var n = k;
        for (; n > 0; n >>= 1, v *= v)
        {
            if ((n & 1) == 1)
                ret = ret * v;
        }
        return ret;
    }
}
#endregion
#region Inverse
public partial struct ModInteger
{
    static public ModInteger Inverse(ModInteger v)
    {
        long p, q;
        ExGCD(v.num, Mod, out p, out q);
        return new ModInteger(p % Mod + Mod);
    }
    static public long ExGCD(long a, long b, out long x, out long y)
    {
        var u = new long[] { a, 1, 0 };
        var v = new long[] { b, 0, 1 };
        while (v[0] != 0)
        {
            var t = u[0] / v[0];
            for (int i = 0; i < 3; i++)
            {
                var tmp = u[i] - t * v[i];
                u[i] = v[i];
                v[i] = tmp;
            }
        }
        x = u[1];
        y = u[2];
        if (u[0] > 0)
            return u[0];
        for (int i = 0; i < 3; i++)
            u[i] = -u[i];
        return u[0];
    }
}
#endregion
#region FNS
public partial class FactorialNumber
{
    int n;
    int[] a;
    public FactorialNumber(int[] perm)
    {
        n = perm.Length;
        var bit = new fenwickTree(n);
        a = new int[n];
        for (int i = n - 1; i >= 0; i--)
        {
            var x = perm[i];
            a[i] = bit[x];
            bit.Add(x, 1);
        }
    }
    public long Add(long k)
    {
        for (int i = 0; i < n; i++)
        {
            var t = k + a[n - 1 - i];
            a[n - 1 - i] = (int)(t % (i + 1));
            k = t / (i + 1);
        }
        return k;
    }
    public override string ToString()
    {
        return string.Join(" ", a);
    }
    #region FenwickTree
    [System.Diagnostics.DebuggerDisplay("Data={ToString()}")]
    public class fenwickTree
    {
        int n;
        int[] bit;
        int max = 1;
        public fenwickTree(int size)
        {
            n = size; bit = new int[n + 1];
            while ((max << 1) <= n) max <<= 1;
        }
        /// <summary>sum[a,b]</summary>
        public int this[int i, int j] { get { return this[j] - this[i - 1]; } }
        /// <summary>sum[0,i]</summary>
        public int this[int i] { get { int s = 0; for (; i > 0; i -= i & -i) s += bit[i]; return s; } }
        public int LowerBound(int w)
        {
            if (w <= 0) return 0;
            int x = 0;
            for (int k = max; k > 0; k >>= 1)
                if (x + k <= n && bit[x + k] < w)
                {
                    w -= bit[x + k];
                    x += k;
                }
            return x + 1;
        }
        /// <summary>add v to bit[i]</summary>
        public void Add(int i, int v)
        {
            if (i == 0) System.Diagnostics.Debug.Fail("BIT is 1 indexed");
            for (; i <= n; i += i & -i) bit[i] += v;
        }
        public override string ToString() { return string.Join(",", Enumerable.Range(0, n + 1).Select(i => this[i, i])); }
    }
    #endregion
}
#endregion
#region FNS Inversion
public partial class FactorialNumber
{
    const int MN = 100050;
    static public ModInteger[] fact;
    static void Build()
    {
        fact = new ModInteger[MN];
        fact[0] = 1;
        for (int i = 1; i < MN; i++)
            fact[i] = i * fact[i - 1];
    }
    public ModInteger GetInversion()
    {
        if (fact == null) Build();
        ModInteger ret = 0;
        ModInteger v = 0;
        ModInteger f = 1;
        for (int i = n - 1; i >= 0; i--)
        {
            var k = n - 1 - i;
            ret += a[i] * fact[k] * k * (k - 1) * ModInteger.Inverse(4);
            ret += f * a[i] * (a[i] - 1) * ModInteger.Inverse(2);
            ret += a[i] * v;
            v += a[i] * f;
            f *= n - i;
        }
        return ret;
    }
}
#endregion
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