yukicoder 0430 文字列検索

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("ABCDABCD");
            WillReturn.Add("3");
            WillReturn.Add("A");
            WillReturn.Add("DA");
            WillReturn.Add("ABCDABCD");
            //4
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("YUKICODER");
            WillReturn.Add("2");
            WillReturn.Add("X");
            WillReturn.Add("ABCDEFGHIJ");
            //0
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("AAAA");
            WillReturn.Add("4");
            WillReturn.Add("A");
            WillReturn.Add("AA");
            WillReturn.Add("AAA");
            WillReturn.Add("AAAA");
            //10
        }
        else if (InputPattern == "Input4") {
            WillReturn.Add("ABAACABCAACBABABACBBAC");
            WillReturn.Add("7");
            WillReturn.Add("A");
            WillReturn.Add("C");
            WillReturn.Add("AA");
            WillReturn.Add("ABB");
            WillReturn.Add("ABA");
            WillReturn.Add("BA");
            WillReturn.Add("CBBAC");
            //26
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static void Main()
    {
        List<string> InputList = GetInputList();
        string S = InputList[0];

        var InsRollingHash = new RollingHash(S);

        int UB = S.Length - 1;

        // 件数[ハッシュ値]なDict
        var CntDict = new Dictionary<decimal, long>();

        for (int LoopRange = 1; LoopRange <= 10; LoopRange++) {
            for (int RangeSta = 0; RangeSta <= UB; RangeSta++) {
                int RangeEnd = RangeSta + LoopRange - 1;
                if (RangeEnd > UB) break;
                decimal Hash = InsRollingHash.GetRangeHash(RangeSta, RangeEnd);
                if (CntDict.ContainsKey(Hash) == false) {
                    CntDict[Hash] = 0;
                }
                CntDict[Hash]++;
            }
        }

        long Answer = 0;
        foreach (string EachStr in InputList.Skip(2)) {
            var CurrRollingHash = new RollingHash(EachStr);
            int RangeSta = 0;
            int RangeEnd = EachStr.Length - 1;
            decimal CurrHash = CurrRollingHash.GetRangeHash(RangeSta, RangeEnd);

            if (CntDict.ContainsKey(CurrHash)) {
                Answer += CntDict[CurrHash];
            }
        }
        Console.WriteLine(Answer);
    }
}

#region RollingHash
// ローリングハッシュ
internal class RollingHash
{
    const decimal Base = 100M;
    const decimal Hou = 67280421310721M;

    // ハッシュ値[終了Ind]で、[0,終了Ind]のハッシュ値を保持
    decimal[] mHashArr;

    // 桁の重みの配列
    decimal[] mOmomiArr;

    // コンストラクタ
    internal RollingHash(string pTargetStr)
    {
        decimal Omomi = 1;
        long UB = pTargetStr.Length - 1;

        mHashArr = new decimal[UB + 1];
        mOmomiArr = new decimal[UB + 1];
        for (int I = 0; I <= UB; I++) {
            mOmomiArr[I] = Omomi;
            if (I > 0) {
                mHashArr[I] += mHashArr[I - 1] * Base;
                mHashArr[I] %= Hou;
            }
            mHashArr[I] += pTargetStr[I];
            mHashArr[I] %= Hou;
            Omomi *= Base;
            Omomi %= Hou;
        }
    }

    // [Sta,End]のハッシュ値を返す
    internal decimal GetRangeHash(long pSta, long pEnd)
    {
        decimal WillReturn = mHashArr[pEnd];
        if (pSta > 0) {
            long Range = pEnd - pSta + 1;
            decimal PrevVal = mHashArr[pSta - 1];
            decimal MinusVal = PrevVal * mOmomiArr[Range];
            MinusVal %= Hou;
            WillReturn -= MinusVal;
            if (WillReturn < 0) {
                WillReturn += Hou;
            }
        }
        return WillReturn;
    }
}
#endregion

解説

ローリングハッシュを使ってます。