第15回PAST J 忍者

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("2 1");
            WillReturn.Add("2 2 1");
            WillReturn.Add("5 2 0");
            //4
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("1 2");
            WillReturn.Add("1 4 1");
            //1
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("4 3");
            WillReturn.Add("5 4 1");
            WillReturn.Add("6 2 0");
            WillReturn.Add("4 5 1");
            WillReturn.Add("3 2 0");
            //25
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static long[] GetSplitArr(string pStr)
    {
        return (pStr == "" ? new string[0] : pStr.Split(' ')).Select(pX => long.Parse(pX)).ToArray();
    }

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

        long[] wkArr = { };
        Action<string> SplitAct = (pStr) => wkArr = GetSplitArr(pStr);

        SplitAct(InputList[0]);

        long Syuriken = wkArr[1];

        var Ins_PQueue_Arr = new PQueue_Arr();
        PQueue_Arr.PQueueJyoutaiDef WillEnqueue;

        foreach (string EachStr in InputList.Skip(1)) {
            SplitAct(EachStr);
            WillEnqueue.Attack = wkArr[0];
            WillEnqueue.HP = wkArr[1];
            WillEnqueue.IsSora = (wkArr[2] == 1);
            WillEnqueue.SortKey = -1;
            WillEnqueue.SortKey = DeriveSortKey(WillEnqueue);
            Ins_PQueue_Arr.Enqueue(WillEnqueue);
        }

        long Answer = 0;
        while (Ins_PQueue_Arr.Count() > 0) {
            PQueue_Arr.PQueueJyoutaiDef Dequeued = Ins_PQueue_Arr.Dequeue();
            if (Dequeued.IsSora) {
                if (Dequeued.HP <= 0) continue;
            }
            else {
                if (Dequeued.HP <= 1) continue;
            }

            // 空にいる魔物に手裏剣を使う場合
            if (Dequeued.IsSora && Syuriken > 0) {
                Syuriken--;
                WillEnqueue.Attack = Dequeued.Attack;
                WillEnqueue.HP = Dequeued.HP - 1;
                WillEnqueue.IsSora = false;
                WillEnqueue.SortKey = -1;
                WillEnqueue.SortKey = DeriveSortKey(WillEnqueue);
                Ins_PQueue_Arr.Enqueue(WillEnqueue);
                continue;
            }

            // 地上にいる魔物に手裏剣を使う場合
            if (Dequeued.IsSora == false && Syuriken > 0) {
                long UseSyuriken = Math.Min(Syuriken, Dequeued.HP - 1);
                Syuriken -= UseSyuriken;
                Dequeued.HP -= UseSyuriken;
            }

            if (Dequeued.IsSora) {
                Answer += Dequeued.HP * Dequeued.Attack;
            }
            else {
                Answer += (Dequeued.HP - 1) * Dequeued.Attack;
            }
        }
        Console.WriteLine(Answer);
    }

    // 倒すまでにかかるコストを返す
    static long DeriveCost(PQueue_Arr.PQueueJyoutaiDef pMonsterInfo)
    {
        if (pMonsterInfo.HP <= 0) return 0;
        if (pMonsterInfo.IsSora == false && pMonsterInfo.HP <= 1) return 0;

        if (pMonsterInfo.IsSora) {
            return pMonsterInfo.HP * pMonsterInfo.Attack;
        }
        else {
            return (pMonsterInfo.HP - 1) * pMonsterInfo.Attack;
        }
    }

    // ソートキーを返す
    static long DeriveSortKey(PQueue_Arr.PQueueJyoutaiDef pMonsterInfo)
    {
        long BeforeCost = DeriveCost(pMonsterInfo);
        PQueue_Arr.PQueueJyoutaiDef AfterMonstr;
        AfterMonstr.Attack = pMonsterInfo.Attack;
        AfterMonstr.HP = pMonsterInfo.HP - 1;
        AfterMonstr.IsSora = false;
        AfterMonstr.SortKey = pMonsterInfo.SortKey;

        long AfterCost = DeriveCost(AfterMonstr);
        return BeforeCost - AfterCost;
    }
}

#region PQueue_Arr
// 内部で配列使用の優先度付きキュー (根のSortKeyが最大)
internal class PQueue_Arr
{
    internal struct PQueueJyoutaiDef
    {
        internal long Attack;
        internal long HP;
        internal bool IsSora;
        internal long SortKey;
    }

    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;
    }

    internal long Count()
    {
        return mHeapArrCnt;
    }

    internal long Peek()
    {
        return mHeapArr[1].SortKey;
    }

    // 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].SortKey < mHeapArr[CurrNode].SortKey) {
            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--;

        MaxHeapify(1);
        return TopNode;
    }

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

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

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

        if (Left <= mHeapArrCnt && mHeapArr[Left].SortKey > Smallest) {
            Smallest = mHeapArr[Left].SortKey;
            SmallestNode = Left;
        }
        if (Right <= mHeapArrCnt && mHeapArr[Right].SortKey > Smallest) {
            Smallest = mHeapArr[Right].SortKey;
            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
            MaxHeapify(SmallestNode);
        }
    }
}
#endregion

解説

手裏剣1枚による、コストの減少量をソートキーとして、
モンスター情報をプライオリティキューに入れて
コストの減少量の降順に手裏剣を使用してます。