ABC326-D ABC Puzzle

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("ABCBC");
            WillReturn.Add("ACAAB");
            //Yes
            //AC..B
            //.BA.C
            //C.BA.
            //BA.C.
            //..CBA
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("3");
            WillReturn.Add("AAA");
            WillReturn.Add("BBB");
            //No
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static string mR;
    static string mC;
    static int UB;

    static List<string> mStrList = new List<string>();

    static void Main()
    {
        List<string> InputList = GetInputList();
        mR = InputList[1];
        mC = InputList[2];
        UB = mR.Length - 1;

        var CharList = new List<char>();
        CharList.Add('A');
        CharList.Add('B');
        CharList.Add('C');
        while (CharList.Count < mR.Length) {
            CharList.Add('.');
        }

        foreach (char[] EachCharArr in RubyPatternClass<char>.Permutation(CharList, CharList.Count)) {
            mStrList.Add(new string(EachCharArr));
        }
        mStrList = mStrList.Distinct().ToList();
        //mStrList.ForEach(pX => Console.WriteLine(pX));

        var Stk = new Stack<JyoutaiDef>();
        JyoutaiDef WillPush;
        WillPush.SelectedIndList = new List<int>();
        Stk.Push(WillPush);

        while (Stk.Count > 0) {
            JyoutaiDef Popped = Stk.Pop();

            int CurrY = Popped.SelectedIndList.Count;

            if (CurrY > UB) {
                // クリア判定
                if (IsOK(Popped)) {
                    return;
                }
                continue;
            }

            for (int I = 0; I <= mStrList.Count - 1; I++) {
                char FirstStrChar = GetFirstStrChar(mStrList[I]);
                if (FirstStrChar != mR[CurrY]) {
                    continue; // 枝切り
                }
                WillPush.SelectedIndList = new List<int>(Popped.SelectedIndList);
                WillPush.SelectedIndList.Add(I);
                Stk.Push(WillPush);
            }
        }
        Console.WriteLine("No");
    }

    struct JyoutaiDef
    {
        internal List<int> SelectedIndList;
    }

    // 文字列の最初の.以外の文字を返す
    static char GetFirstStrChar(string pStr)
    {
        foreach (char EachChar in pStr) {
            if (EachChar != '.') return EachChar;
        }
        return '?';
    }

    // クリア判定
    static bool IsOK(JyoutaiDef pJyoutai)
    {
        char[,] BanArr = new char[UB + 1, UB + 1];
        for (int Y = 0; Y <= UB; Y++) {
            int CurrInd = pJyoutai.SelectedIndList[Y];
            string CurrStr = mStrList[CurrInd];

            for (int X = 0; X <= UB; X++) {
                BanArr[X, Y] = CurrStr[X];
            }
        }

        for (int X = 0; X <= UB; X++) {
            if (IsOKEachCharCnt(X, BanArr) == false) return false;
        }

        for (int X = 0; X <= UB; X++) {
            char FirstRetuChar = GetFirstRetuChar(X, BanArr);
            if (FirstRetuChar != mC[X]) return false;
        }

        Console.WriteLine("Yes");
        PrintBan(BanArr);
        return true;
    }

    // X座標を引数として、列のA,B,Cが1個ずつかを返す
    static bool IsOKEachCharCnt(int pX, char[,] pBanArr)
    {
        int ACnt = 0;
        int BCnt = 0;
        int CCnt = 0;
        for (int Y = 0; Y <= UB; Y++) {
            if (pBanArr[pX, Y] == 'A') ACnt++;
            if (pBanArr[pX, Y] == 'B') BCnt++;
            if (pBanArr[pX, Y] == 'C') CCnt++;
        }
        return ACnt == 1 && BCnt == 1 && CCnt == 1;
    }

    // X座標を引数として、列の最初のA,B,Cを返す
    static char GetFirstRetuChar(int pX, char[,] pBanArr)
    {
        for (int Y = 0; Y <= UB; Y++) {
            if (pBanArr[pX, Y] != '.') return pBanArr[pX, Y];
        }
        return '?';
    }

    ////////////////////////////////////////////////////////////////
    // 2次元配列(char型)のデバッグ出力
    ////////////////////////////////////////////////////////////////
    static void PrintBan(char[,] pBanArr)
    {
        var sb = new System.Text.StringBuilder();
        for (int Y = 0; Y <= pBanArr.GetUpperBound(1); Y++) {
            for (int X = 0; X <= pBanArr.GetUpperBound(0); X++) {
                sb.Append(pBanArr[X, Y]);
            }
            sb.AppendLine();
        }
        Console.Write(sb.ToString());
    }
}

#region RubyPatternClass
// Rubyの場合の数
internal static class RubyPatternClass<Type>
{
    // 順列を返す
    private struct JyoutaiDef_Permutation
    {
        internal List<int> SelectedIndList;
    }
    internal static IEnumerable<Type[]> Permutation(IEnumerable<Type> pEnum, int pR)
    {
        if (pR == 0) yield break;
        Type[] pArr = pEnum.ToArray();
        if (pArr.Length < pR) yield break;

        var Stk = new Stack<JyoutaiDef_Permutation>();
        JyoutaiDef_Permutation WillPush;
        for (int I = pArr.GetUpperBound(0); 0 <= I; I--) {
            WillPush.SelectedIndList = new List<int>() { I };
            Stk.Push(WillPush);
        }

        while (Stk.Count > 0) {
            JyoutaiDef_Permutation Popped = Stk.Pop();

            // クリア判定
            if (Popped.SelectedIndList.Count == pR) {
                var WillReturn = new List<Type>();
                Popped.SelectedIndList.ForEach(X => WillReturn.Add(pArr[X]));
                yield return WillReturn.ToArray();
                continue;
            }

            for (int I = pArr.GetUpperBound(0); 0 <= I; I--) {
                if (Popped.SelectedIndList.Contains(I)) continue;
                WillPush.SelectedIndList = new List<int>(Popped.SelectedIndList) { I };
                Stk.Push(WillPush);
            }
        }
    }
}
#endregion

解説

最初に
ABC.の順列からなる文字列のListを作っておき、
DFSで行ごとに配置してます。

ABC..からなる順列は、5! / 2 = 60 で60通りあり、
60 の 5乗 = 7億ですが
先頭にABCのうちのどれかになるかが決まってるので
7億 / 6 = 1億
となり、4秒の時間制限に間に合います。

文字列というまとまりで考えることで
実装を軽くしてます。