Submission #171729

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Source Code Expand

using System;
using System.IO;
using System.Text;
using System.Linq;
using System.Collections.Generic;

class Program
{
    void Solve()
    {
        int N = reader.Int();
        int[] A = reader.IntArray();
        int maxVal = A.Max();
        if (maxVal > 2000) { throw new ArgumentException(); }

        int[,] dp = new int[N, maxVal + 1];
        dp[0, A[0]] = 1;

        for (int i = 1; i < N; i++)
        {
            int sum = 0;
            for (int x = 0; x <= maxVal; x++)
            {
                Add(ref sum, dp[i - 1, x]);
                if (A[i] == x || A[i] == -1)
                    Add(ref dp[i, x], sum);
            }
        }

        int ans = 0;
        for (int i = 0; i <= maxVal; i++) Add(ref ans, dp[N - 1, i]);

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

    static readonly int Mod = (int)1e9 + 7;
    void Add(ref int a, int b)
    {
        a += b;
        if (a >= Mod) a -= Mod;
    }



    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 string[] s = 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[] IntArray() { return Array.ConvertAll(Line().Split(), int.Parse); }
        public int[][] IntGrid(int H) { return Enumerable.Range(0, H).Select(i => IntArray()).ToArray(); }
        public string[] StringArray(int N) { return Enumerable.Range(0, N).Select(i => Line()).ToArray(); }
        public string Line() { return reader.ReadLine().Trim(); }
        private bool Enqueue()
        {
            if (i < s.Length) return true;
            string line = reader.ReadLine();
            if (string.IsNullOrEmpty(line)) return false;
            s = line.Split(separator, StringSplitOptions.RemoveEmptyEntries);
            i = 0;
            return true;
        }
        private string Dequeue() { Enqueue(); return s[i++]; }
    }
}

Submission Info

Judge Result