#207989 (C#(csc)) No.573 a^2[i] = a[i]

• 問題: No.573 a^2[i] = a[i]
• ユーザー: claw88
• 提出日時: 2017-10-06 22:44:23
• 言語: C#(csc) (csc 3.9.0)
• 結果: AC
• 実行時間: 94 ms / 2,000 ms
• コード長: 2,678 bytes
• コンパイル時間: 946 ms
• コンパイル使用メモリ: 114,280 KB
• 実行使用メモリ: 18,688 KB
• 最終ジャッジ日時: 2024-11-17 01:49:20
• 合計ジャッジ時間: 3,094 ms
• ジャッジサーバーID （参考情報）: judge5 / judge2

ファイルパターン	結果
other	AC * 47

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

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using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using static System.Console;
using Pair = System.Collections.Generic.KeyValuePair<int, int>;
//using System.Numerics;
//using static System.Math;
class Program
{
    static void Main()
    {
        //SetOut(new StreamWriter(OpenStandardOutput()) { AutoFlush = false });
        new Program().solve();
        Out.Flush();
    }
    Scanner cin = new Scanner();
    readonly int[] dd = { 0, 1, 0, -1, 0 };
    readonly int mod = 1000000007;
    readonly string alfa = "abcdefghijklmnopqrstuvwxyz";
    readonly string ALFA = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    int N;
    void solve()
    {
        N = cin.nextint;
        A = new long[N + 1];
        B = new long[N + 1];
        table(N);
        long sum = 0;
        for (int i = 0; i <= N; i++)
        {
            sum += combi(N, i) * powmod(N - i, i, mod) % mod;
            sum %= mod;
            //WriteLine(sum);
        }
        WriteLine(sum);
    }
    long[] A, B;
    //a^b(mod p) solution works in O(logb).
    long powmod(long a, long b, long p)
    {
        if (b == 0) return 1;
        if (b % 2 == 0)
        {
            long d = powmod(a, b / 2, p);
            return d * d % p;
        }
        else
        {
            return a * powmod(a, b - 1, p) % p;
        }
    }
    void table(int n)
    {
        A[0] = 1;
        for (int i = 0; i < n; i++)
        {
            A[i + 1] = A[i] * (i + 1) % mod;
        }
        B[n] = powmod(A[n], mod - 2, mod);
        for (int i = 0; i < n; i++)
        {
            B[n - i - 1] = B[n - i] * (n - i) % mod;
        }
    }
    long combi(int n, int r)
    {
        return A[n] * B[r] % mod * B[n - r] % mod;
    }
}
class Scanner
{
    string[] s; int i;
    char[] cs = new char[] { ' ' };
    public Scanner() { s = new string[0]; i = 0; }
    public string[] scan { get { return ReadLine().Split(); } }
    public int[] scanint { get { return Array.ConvertAll(scan, int.Parse); } }
    public long[] scanlong { get { return Array.ConvertAll(scan, long.Parse); } }
    public double[] scandouble { get { return Array.ConvertAll(scan, double.Parse); } }
    public string next
    {
        get
        {
            if (i < s.Length) return s[i++];
            string st = ReadLine();
            while (st == "") st = ReadLine();
            s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
            i = 0;
            return next;
        }
    }
    public int nextint { get { return int.Parse(next); } }
    public long nextlong { get { return long.Parse(next); } }
    public double nextdouble { get { return double.Parse(next); } }
}
 
 
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