ALDS1_11_D: Connected Components

問題へのリンク

C#のソース

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

// Q039 連結成分 https://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_11_D&lang=jp
class Program
{
    static string InputPattern = "InputX";

    static List<string> GetInputList()
    {
        var WillReturn = new List<string>();

        if (InputPattern == "Input1") {
            WillReturn.Add("10 9");
            WillReturn.Add("0 1");
            WillReturn.Add("0 2");
            WillReturn.Add("3 4");
            WillReturn.Add("5 7");
            WillReturn.Add("5 6");
            WillReturn.Add("6 7");
            WillReturn.Add("6 8");
            WillReturn.Add("7 8");
            WillReturn.Add("8 9");
            WillReturn.Add("3");
            WillReturn.Add("0 1");
            WillReturn.Add("5 9");
            WillReturn.Add("1 3");
            //yes
            //yes
            //no
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    // 隣接リスト
    static Dictionary<int, List<int>> mToNodeListDict = new Dictionary<int, List<int>>();

    static int mN;
    static int mM;

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

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

        SplitAct(InputList[0]);
        mN = wkArr[0];
        mM = wkArr[1];

        foreach (string EachStr in InputList.Skip(1).Take(mM)) {
            SplitAct(EachStr);
            int FromNode = wkArr[0];
            int ToNode = wkArr[1];

            if (mToNodeListDict.ContainsKey(FromNode) == false) {
                mToNodeListDict[FromNode] = new List<int>();
            }
            if (mToNodeListDict.ContainsKey(ToNode) == false) {
                mToNodeListDict[ToNode] = new List<int>();
            }
            mToNodeListDict[FromNode].Add(ToNode);
            mToNodeListDict[ToNode].Add(FromNode);
        }

        ExecDFS(0, mN - 1);

        foreach (string EachStr in InputList.Skip(1 + mM + 1)) {
            SplitAct(EachStr);
            int FromNode = wkArr[0];
            int ToNode = wkArr[1];

            if (mTreeDict[FromNode] == mTreeDict[ToNode]) {
                Console.WriteLine("yes");
            }
            else {
                Console.WriteLine("no");
            }
        }
    }

    // 代表ノード[ノード]なDict
    static Dictionary<int, int> mTreeDict = new Dictionary<int, int>();

    struct JyoutaiDef
    {
        internal int CurrNode;
    }

    // 深さ優先探索を行う
    static void ExecDFS(int pMinNode, int pMaxNode)
    {
        for (int I = pMinNode; I <= pMaxNode; I++) {
            if (mTreeDict.ContainsKey(I)) continue;

            var Stk = new Stack<JyoutaiDef>();
            JyoutaiDef WillPush;
            WillPush.CurrNode = I;
            Stk.Push(WillPush);
            mTreeDict[I] = I;

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

                // 子ノード無しの場合
                if (mToNodeListDict.ContainsKey(Popped.CurrNode) == false)
                    continue;

                foreach (int EachToNode in mToNodeListDict[Popped.CurrNode]) {
                    if (mTreeDict.ContainsKey(EachToNode)) continue;

                    WillPush.CurrNode = EachToNode;
                    Stk.Push(WillPush);
                    mTreeDict[EachToNode] = I;
                }
            }
        }
    }
}

解説

最初に、深さ優先探索の根ノードで分類してます。
それから、各クエリに回答してます。