AOJ 0644 水ようかん

問題へのリンク(AOJ)
問題へのリンク(AtCoder)

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("11");
            WillReturn.Add("2");
            WillReturn.Add("3");
            WillReturn.Add("8");
            WillReturn.Add("4");
            WillReturn.Add("7");
            WillReturn.Add("6");
            WillReturn.Add("6");
            WillReturn.Add("5");
            WillReturn.Add("1");
            WillReturn.Add("7");
            WillReturn.Add("5");
            //2
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("2");
            WillReturn.Add("1");
            WillReturn.Add("10");
            //9
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("5");
            WillReturn.Add("5");
            WillReturn.Add("5");
            WillReturn.Add("5");
            WillReturn.Add("5");
            WillReturn.Add("5");
            //0
        }
        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 long[] mLArr;
    static long UB;

    static long[] mRunSumArr;

    static void Main()
    {
        List<string> InputList = GetInputList();
        mLArr = InputList.Skip(1).Select(pX => long.Parse(pX)).ToArray();
        UB = mLArr.GetUpperBound(0);

        mRunSumArr = (long[])mLArr.Clone();
        for (long I = 1; I <= UB; I++) {
            mRunSumArr[I] += mRunSumArr[I - 1];
        }

        long Answer = long.MaxValue;

        var InsPQueue_Arr = new PQueue_Arr();
        PQueue_Arr.PQueueJyoutaiDef WillEnqueue;
        for (long I = 0; I <= UB; I++) {
            for (long J = I + 1; J <= UB; J++) {
                long RunSum1 = GetRangeSum(0, I);
                long RunSum2 = GetRangeSum(I + 1, J);
                WillEnqueue.CurrInd = J + 1;
                WillEnqueue.Min = Math.Min(RunSum1, RunSum2);
                WillEnqueue.Max = Math.Max(RunSum1, RunSum2);
                WillEnqueue.SortKey = WillEnqueue.Max - WillEnqueue.Min;
                InsPQueue_Arr.Enqueue(WillEnqueue);
            }
        }

        while (InsPQueue_Arr.Count() > 0) {
            PQueue_Arr.PQueueJyoutaiDef Dequeued = InsPQueue_Arr.Dequeue();
            if (Dequeued.CurrInd > UB) {
                Answer = Math.Min(Answer, Dequeued.Max - Dequeued.Min);
                continue;
            }

            // 枝切り
            if (Answer <= Dequeued.Max - Dequeued.Min) continue;

            for (long I = Dequeued.CurrInd; I <= UB; I++) {
                long RunSum = GetRangeSum(Dequeued.CurrInd, I);
                WillEnqueue.CurrInd = I + 1;
                WillEnqueue.Min = Math.Min(Dequeued.Min, RunSum);
                WillEnqueue.Max = Math.Max(Dequeued.Max, RunSum);
                WillEnqueue.SortKey = WillEnqueue.Max - WillEnqueue.Min;
                InsPQueue_Arr.Enqueue(WillEnqueue);
            }
        }
        Console.WriteLine(Answer);
    }

    // 区間和を返す
    static long GetRangeSum(long pSta, long pEnd)
    {
        long RunSum = mRunSumArr[pEnd];
        if (pSta > 0) {
            RunSum -= mRunSumArr[pSta - 1];
        }
        return RunSum;
    }
}

#region PQueue_Arr
// 内部で配列使用の優先度付きキュー (根のValが最小)
internal class PQueue_Arr
{
    internal struct PQueueJyoutaiDef
    {
        internal long CurrInd;
        internal long Min;
        internal long Max;
        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;
    }

    // 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--;

        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].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;
        }

        // 子ノードのほうが小さい場合
        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

最初の2区間を選んだ状態から開始し、
最良優先探索してます。