第12回PAST G Wildcards

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 4 2");
            WillReturn.Add("aabc");
            WillReturn.Add("bbaa");
            WillReturn.Add("abbc");
            WillReturn.Add("cccc");
            WillReturn.Add("acba");
            //3
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("5 4 4");
            WillReturn.Add("aabc");
            WillReturn.Add("bbaa");
            WillReturn.Add("abbc");
            WillReturn.Add("cccc");
            WillReturn.Add("acba");
            //5
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("5 4 0");
            WillReturn.Add("aabc");
            WillReturn.Add("bbaa");
            WillReturn.Add("abbc");
            WillReturn.Add("cccc");
            WillReturn.Add("acba");
            //1
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static void Main()
    {
        List<string> InputList = GetInputList();
        int[] wkArr = InputList[0].Split(' ').Select(pX => int.Parse(pX)).ToArray();
        int L = wkArr[1];
        int K = wkArr[2];

        string[] SArr = InputList.Skip(1).ToArray();

        // K=0 の特殊ケース
        if (K == 0) {
            Console.WriteLine(SArr.Distinct().GroupBy(pX => pX).Max(pX => pX.Count()));
            return;
        }

        var IndList = new List<int>();
        for (int I = 0; I <= SArr[0].Length - 1; I++) {
            IndList.Add(I);
        }

        var AnswerKouho = new List<int>();
        foreach (int[] EachIndArr in RubyPatternClass<int>.Combination(IndList, K)) {
            var CntDict = new Dictionary<string, int>();
            foreach (string EachS in SArr) {
                var sb = new System.Text.StringBuilder();
                for (int I = 0; I <= EachS.Length - 1; I++) {
                    if (Array.IndexOf(EachIndArr, I) >= 0) {
                        continue;
                    }
                    sb.Append(EachS[I]);
                }
                string CurrStr = sb.ToString();
                if (CntDict.ContainsKey(CurrStr) == false) {
                    CntDict[CurrStr] = 0;
                }
                CntDict[CurrStr]++;
            }
            AnswerKouho.Add(CntDict.Values.Max());
        }
        Console.WriteLine(AnswerKouho.Max());
    }
}

#region RubyPatternClass
// Rubyの場合の数
internal static class RubyPatternClass<Type>
{
    // 組合せを返す
    private struct JyoutaiDef_Combination
    {
        internal int CurrP;
        internal List<int> SelectedIndList;
    }
    internal static IEnumerable<Type[]> Combination(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_Combination>();
        JyoutaiDef_Combination WillPush;
        for (int I = pArr.GetUpperBound(0); 0 <= I; I--) {
            WillPush.CurrP = I;
            WillPush.SelectedIndList = new List<int>() { I };
            Stk.Push(WillPush);
        }

        while (Stk.Count > 0) {
            JyoutaiDef_Combination 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); Popped.CurrP + 1 <= I; I--) {
                WillPush.CurrP = I;
                WillPush.SelectedIndList = new List<int>(Popped.SelectedIndList) { I };
                Stk.Push(WillPush);
            }
        }
    }
}
#endregion

解説

?にする位置を決めたら、
?の位置を無視して左から繋いだ文字列の、最頻値の件数が解候補になります。
なので、?の位置を全て試してます。