ABC395-E Flip Edge

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 6 5");
            WillReturn.Add("1 2");
            WillReturn.Add("2 4");
            WillReturn.Add("3 1");
            WillReturn.Add("3 5");
            WillReturn.Add("4 3");
            WillReturn.Add("5 2");
            //4
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("5 6 1");
            WillReturn.Add("1 2");
            WillReturn.Add("2 4");
            WillReturn.Add("3 1");
            WillReturn.Add("3 5");
            WillReturn.Add("4 3");
            WillReturn.Add("5 2");
            //3
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("8 7 613566756");
            WillReturn.Add("2 1");
            WillReturn.Add("2 3");
            WillReturn.Add("4 3");
            WillReturn.Add("4 5");
            WillReturn.Add("6 5");
            WillReturn.Add("6 7");
            WillReturn.Add("8 7");
            //4294967299
        }
        else if (InputPattern == "Input4") {
            WillReturn.Add("20 13 5");
            WillReturn.Add("1 3");
            WillReturn.Add("14 18");
            WillReturn.Add("18 17");
            WillReturn.Add("12 19");
            WillReturn.Add("3 5");
            WillReturn.Add("4 6");
            WillReturn.Add("13 9");
            WillReturn.Add("8 5");
            WillReturn.Add("14 2");
            WillReturn.Add("20 18");
            WillReturn.Add("8 14");
            WillReturn.Add("4 9");
            WillReturn.Add("14 8");
            //21
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static long mN;

    struct EdgeInfoDef
    {
        internal long ToNode;
        internal long Cost;
    }
    static Dictionary<long, List<EdgeInfoDef>> mEdgeInfoListDict = new Dictionary<long, List<EdgeInfoDef>>();

    const long Geta = 1000000;

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

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

        SplitAct(InputList[0]);
        mN = wkArr[0];
        long X = wkArr[2];

        for (long I = 1; I <= mN; I++) {
            mEdgeInfoListDict[I] = new List<EdgeInfoDef>();
            mEdgeInfoListDict[I + Geta] = new List<EdgeInfoDef>();

            EdgeInfoDef WillAdd1;
            WillAdd1.ToNode = I + Geta;
            WillAdd1.Cost = X;
            mEdgeInfoListDict[I].Add(WillAdd1);

            EdgeInfoDef WillAdd2;
            WillAdd2.ToNode = I;
            WillAdd2.Cost = X;
            mEdgeInfoListDict[I + Geta].Add(WillAdd2);
        }

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

            EdgeInfoDef WillAdd1;
            WillAdd1.ToNode = ToNode;
            WillAdd1.Cost = 1;
            mEdgeInfoListDict[FromNode].Add(WillAdd1);

            EdgeInfoDef WillAdd2;
            WillAdd2.ToNode = FromNode + Geta;
            WillAdd2.Cost = 1;
            mEdgeInfoListDict[ToNode + Geta].Add(WillAdd2);
        }

        Dictionary<long, long> Result = Dijkstra(1);

        var AnswerList = new List<long>();
        if (Result.ContainsKey(mN)) AnswerList.Add(Result[mN]);
        if (Result.ContainsKey(mN + Geta)) AnswerList.Add(Result[mN + Geta]);

        Console.WriteLine(AnswerList.Min());
    }

    // ダイクストラ法で、各ノードまでの最短距離を求める
    static Dictionary<long, long> Dijkstra(long pStaNode)
    {
        var InsPQueue = new PQueue_Arr();

        // 距離合計[確定ノード]なDict
        var KakuteiNodeDict = new Dictionary<long, long>();
        KakuteiNodeDict.Add(pStaNode, 0);

        //Enqueue処理
        Action<long> EnqueueAct = pFromNode =>
        {
            if (mEdgeInfoListDict.ContainsKey(pFromNode) == false) {
                return;
            }
            foreach (EdgeInfoDef EachEdge in mEdgeInfoListDict[pFromNode]) {
                // 確定ノードならContinue
                if (KakuteiNodeDict.ContainsKey(EachEdge.ToNode)) continue;

                long wkSumCost = KakuteiNodeDict[pFromNode] + EachEdge.Cost;

                PQueue_Arr.PQueueJyoutaiDef WillEnqueue;
                WillEnqueue.Node = EachEdge.ToNode;
                WillEnqueue.SumCost = wkSumCost;
                InsPQueue.Enqueue(WillEnqueue);
            }
        };
        EnqueueAct(pStaNode);

        while (InsPQueue.IsEmpty() == false) {
            PQueue_Arr.PQueueJyoutaiDef Dequeued = InsPQueue.Dequeue();

            // 確定ノードならcontinue
            if (KakuteiNodeDict.ContainsKey(Dequeued.Node)) continue;

            // 枝切り
            if (KakuteiNodeDict.ContainsKey(mN)) break;
            if (KakuteiNodeDict.ContainsKey(mN + Geta)) break;

            KakuteiNodeDict.Add(Dequeued.Node, Dequeued.SumCost);
            EnqueueAct(Dequeued.Node);
        }

        return KakuteiNodeDict;
    }
}

#region PQueue_Arr
// 内部で配列使用の優先度付きキュー
internal class PQueue_Arr
{
    internal struct PQueueJyoutaiDef
    {
        internal long Node;
        internal long SumCost;
    }

    private PQueueJyoutaiDef[] mHeapArr;
    private long mHeapArrCnt = 0;

    // コンストラクタ
    internal PQueue_Arr()
    {
        mHeapArr = new PQueueJyoutaiDef[65535];
    }
    internal bool IsEmpty()
    {
        return mHeapArrCnt == 0;
    }

    // エンキュー処理
    internal void Enqueue(PQueueJyoutaiDef pAddJyoutai)
    {
        long CurrNode = 1 + mHeapArrCnt;
        if (mHeapArr.GetUpperBound(0) < CurrNode) {
            ExtendArr();
        }
        mHeapArr[CurrNode] = pAddJyoutai;
        mHeapArrCnt++;

        while (1 < CurrNode && mHeapArr[CurrNode / 2].SumCost > mHeapArr[CurrNode].SumCost) {
            PQueueJyoutaiDef Swap = mHeapArr[CurrNode];
            mHeapArr[CurrNode] = mHeapArr[CurrNode / 2];
            mHeapArr[CurrNode / 2] = Swap;

            CurrNode /= 2;
        }
    }

    // 配列のExtend
    private void ExtendArr()
    {
        PQueueJyoutaiDef[] NewHeapArr = new PQueueJyoutaiDef[mHeapArrCnt * 2];
        mHeapArr.CopyTo(NewHeapArr, 0);
        mHeapArr = NewHeapArr;
    }

    // デキュー処理
    internal PQueueJyoutaiDef Dequeue()
    {
        PQueueJyoutaiDef TopNode = mHeapArr[1];
        long LastNode = mHeapArrCnt;
        mHeapArr[1] = mHeapArr[LastNode];
        mHeapArrCnt--;

        MinHeapify(1);
        return TopNode;
    }

    // 根ノードを指定し、根から葉へヒープ構築
    private void MinHeapify(long pRootNode)
    {
        if (mHeapArrCnt <= 1) {
            return;
        }

        long Left = pRootNode * 2;
        long Right = pRootNode * 2 + 1;

        // 左の子、自分、右の子で値が最小のノードを選ぶ
        long Smallest = mHeapArr[pRootNode].SumCost;
        long SmallestNode = pRootNode;

        if (Left <= mHeapArrCnt && mHeapArr[Left].SumCost < Smallest) {
            Smallest = mHeapArr[Left].SumCost;
            SmallestNode = Left;
        }
        if (Right <= mHeapArrCnt && mHeapArr[Right].SumCost < Smallest) {
            Smallest = mHeapArr[Right].SumCost;
            SmallestNode = Right;
        }

        // 子ノードのほうが大きい場合
        if (SmallestNode != pRootNode) {
            PQueueJyoutaiDef Swap = mHeapArr[SmallestNode];
            mHeapArr[SmallestNode] = mHeapArr[pRootNode];
            mHeapArr[pRootNode] = Swap;

            // 再帰的に呼び出し
            MinHeapify(SmallestNode);
        }
    }
}
#endregion

解説

正辺の世界と
逆辺の世界を用意し、
ダイクストラ法を使ってます。