DSL_3_D: Sliding Minimum Elements

問題へのリンク

C#のソース(LinkedListを使う方法)

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("7 3");
            WillReturn.Add("1 7 7 4 8 1 6");
            //1 4 4 1 1
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static void Main()
    {
        List<string> InputList = GetInputList();
        int[] wkArr = InputList[0].Split(' ').Select(pX => int.Parse(pX)).ToArray();
        int L = wkArr[1];

        int[] AArr = InputList[1].Split(' ').Select(pX => int.Parse(pX)).ToArray();
        int UB = AArr.GetUpperBound(0);

        var AnswerList = new List<int>();
        var InsLinkedList = new LinkedList<int>();
        for (int I = 0; I <= UB; I++) {
            // 引退処理
            while (InsLinkedList.Count > 0) {
                int FrontInd = InsLinkedList.First.Value;
                if (I - FrontInd + 1 > L) {
                    InsLinkedList.RemoveFirst();
                    continue;
                }
                break;
            }

            // 押し出し処理
            while (InsLinkedList.Count > 0) {
                int LastInd = InsLinkedList.Last.Value;
                if (AArr[LastInd] > AArr[I]) {
                    InsLinkedList.RemoveLast();
                    continue;
                }
                break;
            }

            // 追加処理
            InsLinkedList.AddLast(I);

            if (I >= L - 1) {
                AnswerList.Add(AArr[InsLinkedList.First.Value]);
            }
        }
        Console.WriteLine(IntEnumJoin(" ", AnswerList));
    }

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

C#のソース(Dequeを使う方法)

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("7 3");
            WillReturn.Add("1 7 7 4 8 1 6");
            //1 4 4 1 1
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static void Main()
    {
        List<string> InputList = GetInputList();
        int[] wkArr = InputList[0].Split(' ').Select(pX => int.Parse(pX)).ToArray();
        int L = wkArr[1];

        int[] AArr = InputList[1].Split(' ').Select(pX => int.Parse(pX)).ToArray();
        int UB = AArr.GetUpperBound(0);

        var AnswerList = new List<int>();
        var InsDeque = new Deque<int>();
        for (int I = 0; I <= UB; I++) {
            // 引退処理
            while (InsDeque.Count > 0) {
                int FrontInd = InsDeque[0];
                if (I - FrontInd + 1 > L) {
                    InsDeque.PopFront();
                    continue;
                }
                break;
            }

            // 押し出し処理
            while (InsDeque.Count > 0) {
                int LastInd = InsDeque[InsDeque.Count - 1];
                if (AArr[LastInd] > AArr[I]) {
                    InsDeque.PopBack();
                    continue;
                }
                break;
            }

            // 追加処理
            InsDeque.PushBack(I);

            if (I >= L - 1) {
                AnswerList.Add(AArr[InsDeque[0]]);
            }
        }
        Console.WriteLine(IntEnumJoin(" ", AnswerList));
    }

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

#region Deque
internal class Deque<T>
{
    T[] buf;
    int offset, count, capacity;

    internal int Count { get { return count; } }

    internal Deque(int cap) { buf = new T[capacity = cap]; }

    internal Deque() { buf = new T[capacity = 16]; }

    internal T this[int index]
    {
        get { return buf[GetIndex(index)]; }
        set { buf[GetIndex(index)] = value; }
    }

    private int GetIndex(int index)
    {
        if (index >= capacity)
            throw new IndexOutOfRangeException("out of range");
        int ret = index + offset;
        if (ret >= capacity)
            ret -= capacity;
        return ret;
    }

    internal void PushFront(T item)
    {
        if (count == capacity) Extend();
        if (--offset < 0) offset += buf.Length;
        buf[offset] = item;
        count++;
    }

    internal T PopFront()
    {
        if (count == 0)
            throw new InvalidOperationException("collection is empty");
        count--;
        T ret = buf[offset++];
        if (offset >= capacity) offset -= capacity;
        return ret;
    }

    internal void PushBack(T item)
    {
        if (count == capacity) Extend();
        int id = count + offset;
        count++;
        if (id >= capacity) id -= capacity;
        buf[id] = item;
    }

    internal T PopBack()
    {
        if (count == 0)
            throw new InvalidOperationException("collection is empty");
        return buf[GetIndex(--count)];
    }

    internal void Insert(int index, T item)
    {
        if (index > count) throw new IndexOutOfRangeException();
        this.PushFront(item);
        for (int i = 0; i < index; i++)
            this[i] = this[i + 1];
        this[index] = item;
    }

    internal T RemoveAt(int index)
    {
        if (index < 0 || index >= count) throw new IndexOutOfRangeException();
        T ret = this[index];
        for (int i = index; i > 0; i--)
            this[i] = this[i - 1];
        this.PopFront();
        return ret;
    }

    private void Extend()
    {
        T[] newBuffer = new T[capacity << 1];
        if (offset > capacity - count) {
            int len = buf.Length - offset;
            Array.Copy(buf, offset, newBuffer, 0, len);
            Array.Copy(buf, 0, newBuffer, len, count - len);
        }
        else Array.Copy(buf, offset, newBuffer, 0, count);
        buf = newBuffer;
        offset = 0;
        capacity <<= 1;
    }

    internal T[] Items//デバッグ時に中身を調べるためのプロパティ
    {
        get
        {
            T[] a = new T[count];
            for (int i = 0; i < count; i++)
                a[i] = this[i];
            return a;
        }
    }
}
#endregion

解説

スライド最小値なので
LinkedListかDequeを使って求めることができます。