ABC315-D Magical Cookies

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 3");
            WillReturn.Add("aaa");
            WillReturn.Add("aaa");
            WillReturn.Add("abc");
            WillReturn.Add("abd");
            //2
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("2 5");
            WillReturn.Add("aaaaa");
            WillReturn.Add("abcde");
            //4
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("3 3");
            WillReturn.Add("ooo");
            WillReturn.Add("ooo");
            WillReturn.Add("ooo");
            //0
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static char[,] mBanArr;
    static int UB_X;
    static int UB_Y;

    static HashSet<int> mXSet = new HashSet<int>();
    static HashSet<int> mYSet = new HashSet<int>();

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

        mBanArr = CreateBanArr(InputList.Skip(1));
        UB_X = mBanArr.GetUpperBound(0);
        UB_Y = mBanArr.GetUpperBound(1);

        var XList = new List<int>();
        var YList = new List<int>();
        for (int I = 0; I <= UB_X; I++) XList.Add(I);
        for (int I = 0; I <= UB_Y; I++) YList.Add(I);

        // X座標とY座標を、ランダマイズソート
        foreach (int X in XList.OrderBy(pX => Guid.NewGuid())) mXSet.Add(X);
        foreach (int Y in YList.OrderBy(pX => Guid.NewGuid())) mYSet.Add(Y);

        while (true) {
            HashSet<int> Set1 = ExecTate();
            HashSet<int> Set2 = ExecYoko();

            if (Set1.Count == 0 && Set2.Count == 0) {
                break;
            }
            mYSet.ExceptWith(Set1);
            mXSet.ExceptWith(Set2);
        }

        long Answer = mXSet.Count * mYSet.Count;
        Console.WriteLine(Answer);
    }

    // Y座標ごとにチェックし、マークしたY座標のSetを返す
    static HashSet<int> ExecTate()
    {
        var WillReturn = new HashSet<int>();
        if (mXSet.Count >= 2) {
            foreach (int EachY in mYSet) {
                var CharSet = new HashSet<char>();
                foreach (int EachX in mXSet) {
                    CharSet.Add(mBanArr[EachX, EachY]);
                    if (CharSet.Count == 2) break;
                }
                if (CharSet.Count == 1) {
                    WillReturn.Add(EachY);
                }
            }
        }
        return WillReturn;
    }

    // X座標ごとにチェックし、マークしたX座標のSetを返す
    static HashSet<int> ExecYoko()
    {
        var WillReturn = new HashSet<int>();
        if (mYSet.Count >= 2) {
            foreach (int EachX in mXSet) {
                var CharSet = new HashSet<char>();
                foreach (int EachY in mYSet) {
                    CharSet.Add(mBanArr[EachX, EachY]);
                    if (CharSet.Count == 2) break;
                }
                if (CharSet.Count == 1) {
                    WillReturn.Add(EachX);
                }
            }
        }
        return WillReturn;
    }

    ////////////////////////////////////////////////////////////////
    // IEnumerable<string>をcharの2次元配列に設定する
    ////////////////////////////////////////////////////////////////
    static char[,] CreateBanArr(IEnumerable<string> pStrEnum)
    {
        var StrList = pStrEnum.ToList();
        if (StrList.Count == 0) {
            return new char[0, 0];
        }
        int UB_X = StrList[0].Length - 1;
        int UB_Y = StrList.Count - 1;

        char[,] WillReturn = new char[UB_X + 1, UB_Y + 1];

        for (int Y = 0; Y <= UB_Y; Y++) {
            for (int X = 0; X <= UB_X; X++) {
                WillReturn[X, Y] = StrList[Y][X];
            }
        }
        return WillReturn;
    }
}

解説

クイックソートの最悪計算量の回避の感覚で
X座標とY座標をランダムな順序で見るようにしてます。