結果
| 問題 | No.660 家を通り過ぎないランダムウォーク問題 |
| ユーザー |
 紙ぺーぱー
|
| 提出日時 | 2018-03-03 00:17:35 |
| 言語 | C#(csc) (csc 3.9.0) |
| 結果 |
AC
|
| 実行時間 | 57 ms / 2,000 ms |
| コード長 | 5,801 bytes |
| コンパイル時間 | 2,337 ms |
| コンパイル使用メモリ | 110,848 KB |
| 実行使用メモリ | 30,516 KB |
| 最終ジャッジ日時 | 2024-06-23 01:01:54 |
| 合計ジャッジ時間 | 3,629 ms |
|
ジャッジサーバーID （参考情報） |
judge4 / judge2 |
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| ファイルパターン | 結果 |
|---|---|
| other | AC * 45 |
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
using System;
using System.Linq;
using System.Collections.Generic;
using Debug = System.Diagnostics.Debug;
using SB = System.Text.StringBuilder;
using Number = System.Int64;
namespace Program {
public class Solver {
Random rnd = new Random(0);
public void Solve() {
var n = ri;
ModInt ans = 0;
var binom = new BinomialCoefficient(2 * n + 5);
for (int i = 0; i <= n; i++)
{
var N = n + i;
var k = i;
if (N + k > 2 * n) break;
N--;
ModInt v = binom.fact[N + k];
v *= (N - k + 1);
v *= binom.ifact[k];
v *= binom.ifact[N + 1];
Debug.WriteLine(v);
ans += v;
}
Console.WriteLine(ans);
}
const long INF = 1L << 60;
static int[] dx = { -1, 0, 1, 0 };
static int[] dy = { 0, 1, 0, -1 };
int ri { get { return sc.Integer(); } }
long rl { get { return sc.Long(); } }
double rd { get { return sc.Double(); } }
string rs { get { return sc.Scan(); } }
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(ie.ToArray()); }
static public string AsJoinedString<T>(this IEnumerable<T> ie, string st = " ") {
return string.Join(st, ie);
}
static public void Main() {
Console.SetOut(new Program.IO.Printer(Console.OpenStandardOutput()) { AutoFlush = true });
var solver = new Program.Solver();
try
{
solver.Solve();
Console.Out.Flush();
}
catch { }
}
}
#endregion
#region Ex
namespace Program.IO {
using System.IO;
using System.Text;
using System.Globalization;
public class Printer: StreamWriter {
public override IFormatProvider FormatProvider { get { return CultureInfo.InvariantCulture; } }
public Printer(Stream stream) : base(stream, new UTF8Encoding(false, true)) { }
}
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 != 0; b = (char)read()) if (b != '\r') sb.Append(b);
return sb.ToString();
}
public long Long() { return isEof ? long.MinValue : long.Parse(Scan()); }
public int Integer() { return isEof ? int.MinValue : int.Parse(Scan()); }
public double Double() { return isEof ? double.NaN : double.Parse(Scan(), CultureInfo.InvariantCulture); }
}
}
#endregion
#region ModInt
public struct ModInt {
public const long Mod = (int)1e9 + 7;
public long num;
public ModInt(long n) { num = n; }
public override string ToString() { return num.ToString(); }
public static ModInt operator +(ModInt l, ModInt r) { l.num += r.num; if (l.num >= Mod) l.num -= Mod; return l; }
public static ModInt operator -(ModInt l, ModInt r) { l.num -= r.num; if (l.num < 0) l.num += Mod; return l; }
public static ModInt operator *(ModInt l, ModInt r) { return new ModInt(l.num * r.num % Mod); }
public static implicit operator ModInt(long n) { n %= Mod; if (n < 0) n += Mod; return new ModInt(n); }
public static ModInt Pow(ModInt v, long k) { return Pow(v.num, k); }
public static ModInt Pow(long v, long k) {
long ret = 1;
for (k %= Mod - 1; k > 0; k >>= 1, v = v * v % Mod)
if ((k & 1) == 1) ret = ret * v % Mod;
return new ModInt(ret);
}
public static ModInt Inverse(ModInt v) { return Pow(v, Mod - 2); }
}
#endregion
#region Binomial Coefficient
public class BinomialCoefficient {
public ModInt[] fact, ifact;
public BinomialCoefficient(int n) {
fact = new ModInt[n + 1];
ifact = new ModInt[n + 1];
fact[0] = 1;
for (int i = 1; i <= n; i++)
fact[i] = fact[i - 1] * i;
ifact[n] = ModInt.Inverse(fact[n]);
for (int i = n - 1; i >= 0; i--)
ifact[i] = ifact[i + 1] * (i + 1);
ifact[0] = ifact[1];
}
public ModInt this[int n, int r] {
get {
if (n < 0 || n >= fact.Length || r < 0 || r > n) return 0;
return fact[n] * ifact[n - r] * ifact[r];
}
}
public ModInt RepeatedCombination(int n, int k) {
if (k == 0) return 1;
return this[n + k - 1, k];
}
}
#endregion