Submission #1535004

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Source Code Expand

using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Globalization;
using System.Diagnostics;
using static System.Console;
using Pair = System.Collections.Generic.KeyValuePair<int, int>;
//using System.Numerics;

class Program
{
    static void Main()
    {
        //SetOut(new StreamWriter(OpenStandardOutput()) { AutoFlush = false });
        new Program().solve();
        Out.Flush();
    }
    Scanner cin = new Scanner();
    Random rnd = new Random();
    Stopwatch sw = new Stopwatch();
    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;
        var A = cin.scanint;
        var B = new int[N];
        foreach (var item in A)
        {
            B[item]++;
        }
        bool flag = true;
        if (N % 2 == 0 && B[0] != 0) flag = false;
        if (N % 2 == 1 && B[0] != 1) flag = false;


        for (int i = 1 + (N % 2); i < N; i += 2)
        {
            //WriteLine(i + " " + B[i]);
            if (B[i] != 2) flag = false;
        }

        if (flag)
        {
            long ans = 1;
            for (int i = 0; i < N / 2; i++)
            {
                ans *= 2;
                ans %= mod;
            }
            WriteLine(ans);
        }
        else
        {
            WriteLine(0);
        }
    }


}

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); } }
}

Submission Info

Judge Result