ABC350-C Sort

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

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

        // Ind[値]なDict
        var IndDict = new Dictionary<int, int>();
        for (int I = 0; I <= AArr.GetUpperBound(0); I++) {
            IndDict[AArr[I]] = I;
        }

        int MinVal = AArr.Min();
        int MaxVal = AArr.Max();

        var SwapStrList = new List<string>();
        for (int I = MinVal; I <= MaxVal; I++) {
            if (AArr[I - 1] == I) continue;

            int FromInd = I - 1;
            int ToInd = IndDict[I];
            SwapStrList.Add(string.Format("{0} {1}", FromInd + 1, ToInd + 1));

            // 値のSwap
            int wkVal = AArr[FromInd];
            AArr[FromInd] = AArr[ToInd];
            AArr[ToInd] = wkVal;

            IndDict[wkVal] = ToInd;
            IndDict[FromInd] = I;
        }
        Console.WriteLine(SwapStrList.Count);
        SwapStrList.ForEach(pX => Console.WriteLine(pX));
    }
}

解説

最小値選択法をシュミレーションしてます。
Ind[値]なDictでの高速化もしてます。