第10回PAST H 連結成分

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 7");
            WillReturn.Add("1 1 2");
            WillReturn.Add("2 2");
            WillReturn.Add("1 3 4");
            WillReturn.Add("2 5");
            WillReturn.Add("1 1 4");
            WillReturn.Add("2 1");
            WillReturn.Add("2 4");
            //1 2
            //5
            //1 2 3 4
            //1 2 3 4
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("1 2");
            WillReturn.Add("2 1");
            WillReturn.Add("2 1");
            //1
            //1
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("3 3");
            WillReturn.Add("1 1 2");
            WillReturn.Add("2 1");
            WillReturn.Add("1 1 2");
            //1 2
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static void Main()
    {
        List<string> InputList = GetInputList();

        int[] wkArr = { };
        Action<string> SplitAct = pStr =>
            wkArr = pStr.Split(' ').Select(pX => int.Parse(pX)).ToArray();

        SplitAct(InputList[0]);
        int N = wkArr[0];

        var InsUnionFind = new UnionFind();
        for (int I = 1; I <= N; I++) {
            InsUnionFind.MakeSet(I);
        }

        foreach (string EachStr in InputList.Skip(1)) {
            SplitAct(EachStr);
            int T = wkArr[0];
            if (T == 1) {
                int FromNode = wkArr[1];
                int ToNode = wkArr[2];
                InsUnionFind.Unite(FromNode, ToNode);
            }
            if (T == 2) {
                int BaseNode = wkArr[1];
                InsUnionFind.PrintNodeList(BaseNode);
            }
        }
    }
}

// UnionFindクラス
internal class UnionFind
{
    private class NodeInfoDef
    {
        internal long ParentNode;
        internal long Rank;
        internal List<long> NodeList;
    }
    private Dictionary<long, NodeInfoDef> mNodeInfoDict =
        new Dictionary<long, NodeInfoDef>();

    // 要素が1つである木を森に追加
    internal void MakeSet(long pNode)
    {
        NodeInfoDef WillAdd = new NodeInfoDef();
        WillAdd.ParentNode = pNode;
        WillAdd.Rank = 0;
        WillAdd.NodeList = new List<long>() { pNode };
        mNodeInfoDict[pNode] = WillAdd;
    }

    // 合併処理
    internal void Unite(long pX, long pY)
    {
        long XNode = FindSet(pX);
        long YNode = FindSet(pY);

        // 既に同じ木の場合
        if (XNode == YNode) return;

        long XRank = mNodeInfoDict[XNode].Rank;
        long YRank = mNodeInfoDict[YNode].Rank;

        if (XRank > YRank) {
            mNodeInfoDict[YNode].ParentNode = XNode;
            mNodeInfoDict[XNode].NodeList.AddRange(mNodeInfoDict[YNode].NodeList);
        }
        else {
            mNodeInfoDict[XNode].ParentNode = YNode;
            mNodeInfoDict[YNode].NodeList.AddRange(mNodeInfoDict[XNode].NodeList);
            if (XRank == YRank) {
                mNodeInfoDict[YNode].Rank++;
            }
        }
    }

    // ノードを引数として、木の根を取得
    internal long FindSet(long pTargetNode)
    {
        // 根までの経路上のノードのList
        var PathNodeList = new List<long>();

        long CurrNode = pTargetNode;
        while (CurrNode != mNodeInfoDict[CurrNode].ParentNode) {
            PathNodeList.Add(CurrNode);
            CurrNode = mNodeInfoDict[CurrNode].ParentNode;
        }

        // 経路圧縮 (親ポインタの付け替え)
        foreach (long EachPathNode in PathNodeList) {
            mNodeInfoDict[EachPathNode].ParentNode = CurrNode;
        }
        return CurrNode;
    }

    internal void DebugPrint()
    {
        foreach (var EachPair in mNodeInfoDict.OrderBy(pX => pX.Key)) {
            Console.WriteLine("mNodeInfoDict[{0}].ParentNode={1}",
                EachPair.Key, EachPair.Value.ParentNode);
        }
    }

    internal void PrintNodeList(long pBaseNode)
    {
        long RootNode = FindSet(pBaseNode);
        mNodeInfoDict[RootNode].NodeList.Sort();

        // セパレータとLong型の列挙を引数として、結合したstringを返す
        Func<string, IEnumerable<long>, string> LongEnumJoin = (pSeparater, pEnum) =>
        {
            string[] StrArr = Array.ConvertAll(pEnum.ToArray(), pX => pX.ToString());
            return string.Join(pSeparater, StrArr);
        };

        Console.WriteLine(LongEnumJoin(" ", mNodeInfoDict[RootNode].NodeList));
    }
}

解説

UnionFindで連結成分を管理してます。