Q40 並べ替えの繰り返し

C#のソース

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        int AnswerCnt = int.MinValue;
        foreach (List<int> EachJyunretuList in DeriveJyunretuListEnum()) {
            int ChangeCnt = 0;
            List<int> wkList = new List<int>(EachJyunretuList);
            int FirstNum = wkList[0];
            while (FirstNum != 1) {
                int[] wkArr = wkList.Take(FirstNum).Reverse().ToArray();
                wkList.RemoveRange(0, FirstNum);
                wkList.InsertRange(0, wkArr);

                ChangeCnt++;
                FirstNum = wkList[0];
            }

            if (AnswerCnt <= ChangeCnt) {
                AnswerCnt = ChangeCnt;
                var sb = new System.Text.StringBuilder();
                sb.AppendFormat("並べ替えの回数={0}の解候補を発見。", ChangeCnt);
                EachJyunretuList.ForEach(X => sb.AppendFormat("{0},", X));
                Console.WriteLine(sb.ToString());
            }
        }
    }

    struct JyoutaiDef
    {
        internal List<int> NumList;
    }

    //1から9の順列を列挙
    static IEnumerable<List<int>> DeriveJyunretuListEnum()
    {
        var stk = new Stack<JyoutaiDef>();
        JyoutaiDef WillPush;
        WillPush.NumList = new List<int>();
        stk.Push(WillPush);

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

            //クリア判定
            if (Popped.NumList.Count == 9) {
                yield return Popped.NumList;
                continue;
            }

            for (int I = 1; I <= 9; I++) {
                if (Popped.NumList.Contains(I)) continue;

                WillPush.NumList = new List<int>(Popped.NumList);
                WillPush.NumList.Add(I);
                stk.Push(WillPush);
            }
        }
    }
}

実行結果

省略
並べ替えの回数=28の解候補を発見。8,6,1,3,7,2,9,5,4,
並べ替えの回数=28の解候補を発見。8,6,1,2,7,5,9,3,4,
並べ替えの回数=28の解候補を発見。8,6,1,2,3,7,9,5,4,
並べ替えの回数=28の解候補を発見。7,2,9,5,1,6,8,3,4,
並べ替えの回数=30の解候補を発見。6,1,5,9,7,2,8,3,4,

解説

9の階乗は、362880なので、
深さ優先探索で、列挙オブジェクトを返してます。