ARC197-A Union of Grid Paths

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("4");
            WillReturn.Add("4 5");
            WillReturn.Add("D?DRR?R");
            WillReturn.Add("4 5");
            WillReturn.Add("DDRRDRR");
            WillReturn.Add("4 5");
            WillReturn.Add("???????");
            WillReturn.Add("2 2");
            WillReturn.Add("DR");
            //12
            //8
            //20
            //3
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static long[] GetSplitArr(string pStr)
    {
        return (pStr == "" ? new string[0] : pStr.Split(' ')).Select(pX => long.Parse(pX)).ToArray();
    }

    static void Main()
    {
        List<string> InputList = GetInputList();

        long[] wkArr = { };
        Action<string> SplitAct = (pStr) => wkArr = GetSplitArr(pStr);

        for (int I = 1; I <= InputList.Count - 1; I += 2) {
            SplitAct(InputList[I]);
            long H = wkArr[0];
            long W = wkArr[1];
            string S = InputList[I + 1];
            long Answer = Solve(H, W, S);
            Console.WriteLine(Answer);
        }
    }

    static long Solve(long pH, long pW, string pS)
    {
        var MinYDict = new Dictionary<long, long>();
        var MaxYDict = new Dictionary<long, long>();

        for (long X = 1; X <= pW; X++) {
            MinYDict[X] = long.MaxValue;
            MaxYDict[X] = long.MinValue;
        }
        MinYDict[1] = 1;
        MaxYDict[1] = 1;

        char[] SArr = pS.ToArray();

        long DCnt = SArr.Count(pX => pX == 'D');
        long RCnt = SArr.Count(pX => pX == 'R');

        Action<bool> MoveAct = (pHasPriorityDown) =>
        {
            long RestD = pH - 1 - DCnt;
            long RestR = pW - 1 - RCnt;

            long CurrX = 1;
            long CurrY = 1;

            foreach (char EachChar in SArr) {
                if (EachChar == 'D') {
                    CurrY++;
                }
                if (EachChar == 'R') {
                    CurrX++;
                }
                if (EachChar == '?') {
                    if (pHasPriorityDown) {
                        if (0 < RestD) {
                            CurrY++;
                            RestD--;
                        }
                        else {
                            CurrX++;
                        }
                    }
                    if (pHasPriorityDown == false) {
                        if (0 < RestR) {
                            CurrX++;
                            RestR--;
                        }
                        else {
                            CurrY++;
                        }
                    }
                }

                MinYDict[CurrX] = Math.Min(CurrY, MinYDict[CurrX]);
                MaxYDict[CurrX] = Math.Max(CurrY, MaxYDict[CurrX]);
            }
        };
        MoveAct(false);
        MoveAct(true);

        long Answer = 0;
        for (long X = 1; X <= pW; X++) {
            Answer += MaxYDict[X] - MinYDict[X] + 1;
        }
        return Answer;
    }
}

解説

下移動を優先するパスと
右移動を優先するパスで

Y座標の最小値[X座標]なDictと
Y座標の最大値[X座標]なDictを求めます。

そして、X座標ごとの(Y座標の最大値 - Y座標の最小値 + 1)
の総和が解になります。