Submission #190259

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Source Code Expand

using System;
using System.IO;
using System.Text;
using System.Linq;
using System.Collections.Generic;
using Enu = System.Linq.Enumerable;

class Program
{
    void Solve()
    {
        int N = reader.Int(), Move = reader.Int();
        int X = Math.Abs(reader.Int()), Y = Math.Abs(reader.Int());
        int NeedR = X / Move, NeedU = Y / Move;
        int minNeed = NeedR + NeedU;

        if (X % Move != 0 || Y % Move != 0 || minNeed > N)
        {
            Console.WriteLine(0); return;
        }

        double all = 0;
        double[] fact = new double[N + 1];
        for (int i = 1; i <= N; i++)
        {
            fact[i] = fact[i - 1] + Math.Log(i);
            all += Math.Log(4);
        }

        double ans = 0;
        for (int LR = 0; LR * 2 <= N; LR++)
            for (int UD = 0; UD * 2 + LR * 2 <= N; UD++)
            {
                int L = LR + NeedR;
                int R = LR;
                int U = UD + NeedU;
                int D = UD;
                int rem = L + R + U + D;
                if (rem != N) continue;
                double c = Math.Exp(fact[N] - fact[L] - fact[R] - fact[U] - fact[D] - all);
                ans += c;
            }

        Console.WriteLine(ans);
        Console.ReadLine();
    }



    static void Main() { new Program().Solve(); }
    static Reader reader = new Reader(Console.In);

    class Reader
    {
        private readonly TextReader reader;
        private readonly char[] separator = new char[] { ' ' };
        private readonly StringSplitOptions removeOp = StringSplitOptions.RemoveEmptyEntries;
        private string[] A = new string[0];
        private int i;

        public Reader(TextReader r) { reader = r; }
        public bool HasNext() { return Enqueue(); }
        public string String() { return Dequeue(); }
        public int Int() { return int.Parse(Dequeue()); }
        public long Long() { return long.Parse(Dequeue()); }
        public double Double() { return double.Parse(Dequeue()); }
        public int[] IntLine() { var s = Line(); return s == "" ? new int[0] : Array.ConvertAll(Split(s), int.Parse); }
        public int[] IntArray(int N) { return Enumerable.Range(0, N).Select(i => Int()).ToArray(); }
        public int[][] IntGrid(int H) { return Enumerable.Range(0, H).Select(i => IntLine()).ToArray(); }
        public string[] StringArray(int N) { return Enumerable.Range(0, N).Select(i => Line()).ToArray(); }
        public string Line() { return reader.ReadLine().Trim(); }
        private string[] Split(string s) { return s.Split(separator, removeOp); }
        private bool Enqueue()
        {
            if (i < A.Length) return true;
            string line = reader.ReadLine();
            if (line == null) return false;
            if (line == "") return Enqueue();
            A = Split(line);
            i = 0;
            return true;
        }
        private string Dequeue() { Enqueue(); return A[i++]; }
    }

}

Submission Info

Judge Result