yukicoder 0326 あみだますたー

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("6");
            WillReturn.Add("1 2");
            WillReturn.Add("3 4");
            WillReturn.Add("2 3");
            WillReturn.Add("3 4");
            WillReturn.Add("1 2");
            WillReturn.Add("4 5");
            WillReturn.Add("5 1 4 3 2");
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("6");
            WillReturn.Add("4");
            WillReturn.Add("1 2");
            WillReturn.Add("2 3");
            WillReturn.Add("5 6");
            WillReturn.Add("3 4");
            WillReturn.Add("2 6 3 1 5 4");
        }
        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);

        long N = long.Parse(InputList[0]);
        long K = long.Parse(InputList[1]);
        long[] AArr = GetSplitArr(InputList.Last());

        var GoalDict = new Dictionary<long, long>();
        for (long I = 0; I <= AArr.GetUpperBound(0); I++) {
            GoalDict[AArr[I]] = I + 1;
        }

        var CurrDict = new Dictionary<long, long>();
        for (long I = 1; I <= N; I++) {
            CurrDict[I] = I;
        }

        foreach (string EachStr in InputList.Skip(2).Take((int)K)) {
            SplitAct(EachStr);
            long L = wkArr[0];
            long R = wkArr[1];
            long tmp = CurrDict[L];
            CurrDict[L] = CurrDict[R];
            CurrDict[R] = tmp;
        }

        var AnswerList = new List<long>();
        for (long I = 1; I <= N; I++) {
            long SearchVal = GoalDict[I];
            long StaInd = 0;
            for (long J = I + 1; J <= N; J++) {
                if (CurrDict[J] == SearchVal) {
                    StaInd = J;
                    break;
                }
            }
            // 既にゴールにいる場合
            if (I == StaInd) continue;

            for (long J = StaInd; I + 1 <= J; J--) {
                // 三角交換
                long tmp = CurrDict[J];
                CurrDict[J] = CurrDict[J - 1];
                CurrDict[J - 1] = tmp;

                AnswerList.Add(J - 1);
            }
        }
        Console.WriteLine(AnswerList.Count);
        foreach (long EachL in AnswerList) {
            Console.WriteLine("{0} {1}", EachL, EachL + 1);
        }
    }
}

解説

バブルソートをシュミれば最小の交換回数として
解くことができます。