ABC369-D Bonus EXP

問題へのリンク

C#のソース

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static string InputPattern = "InputX";

    static List<string> GetInputList()
    {
        var WillReturn = new List<string>();

        if (InputPattern == "Input1") {
            WillReturn.Add("5");
            WillReturn.Add("1 5 3 2 7");
            //28
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("2");
            WillReturn.Add("1000000000 1000000000");
            //3000000000
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static void Main()
    {
        List<string> InputList = GetInputList();
        long[] AArr = InputList[1].Split(' ').Select(pX => long.Parse(pX)).ToArray();

        // スコア[次に倒すモンスター]なDP表
        var PrevDP = new Dictionary<long, long>();
        PrevDP[1] = 0;

        foreach (long EachA in AArr) {
            var CurrDP = new Dictionary<long, long>(PrevDP);
            foreach (var EachPair in PrevDP) {
                long NewVal = EachPair.Value + EachA;
                if (EachPair.Key == 2) {
                    NewVal += EachA;
                }
                long NewKey = EachPair.Key + 1;
                if (NewKey == 3) NewKey = 1;

                if (CurrDP.ContainsKey(NewKey)) {
                    if (CurrDP[NewKey] >= NewVal) {
                        continue;
                    }
                }
                CurrDP[NewKey] = NewVal;
            }
            PrevDP = CurrDP;
        }
        Console.WriteLine(PrevDP.Values.Max());
    }
}

解説

スコア[次に倒すモンスター]でDPしてます。