結果

問題 No.778 クリスマスツリー
コンテスト
ユーザー ひばち
提出日時 2019-08-22 01:49:42
言語 C#(csc)
(csc 3.9.0)
結果
AC  
実行時間 453 ms / 2,000 ms
コード長 8,662 bytes
コンパイル時間 2,282 ms
コンパイル使用メモリ 113,024 KB
実行使用メモリ 94,456 KB
最終ジャッジ日時 2024-10-14 02:00:30
合計ジャッジ時間 6,203 ms
ジャッジサーバーID
（参考情報） 		judge3 / judge2
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 12
権限があれば一括ダウンロードができます
コンパイルメッセージ
Microsoft (R) Visual C# Compiler version 3.9.0-6.21124.20 (db94f4cc)
Copyright (C) Microsoft Corporation. All rights reserved.

ソースコード

diff # 

using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using static System.Console;
using static System.Convert;
using static System.Math;
//using static System.Globalization.CultureInfo;
using System.Text;
class Program
{
    private static void chmin<T>(ref T num, T val) where T : IComparable<T>
        => num = num.CompareTo(val) == 1 ? val : num;
    private static void chmax<T>(ref T num, T val) where T : IComparable<T>
        => num = num.CompareTo(val) == -1 ? val : num;
    private static void swap<T>(ref T v1,ref T v2)
    { var t = v2;v2 = v1;v1 = t; }
    static void Main(string[] args)
    {
        var pr = new Program();
        var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
        Console.SetOut(sw);
        pr.Solve();
        Console.Out.Flush();
    }
    void Solve()
    {
        var num = Input.num;
        var t = new Tree(num);
        var b = new BIT(num+1);
        for (var i = 0; i < num - 1; i++)
            t.AddEdge(Input.Next<int>(), i + 1, directed: true);
        var li = t.EularTour(0);
        var st = new Stack<int>();
        b.add(1, 1);
        st.Push(0);
        var res = 0L;
        for(var i = 1; i < li.Count; i++)
        {
            if(st.Peek()==li[i])
            { st.Pop();b.add(li[i] + 1, -1);continue; }
            res += b[li[i]];
            b.add(li[i] + 1, 1);
            st.Push(li[i]);
        }
        WriteLine(res);
    }
}

public class Tree
{
    public List<Pair<long, int>>[] edge;
    private List<int> etList;
    public int Count { get; }
    public Tree(int num)
    {
        Count = num;
        edge = Enumerable.Repeat(0, num).Select(_ => new List<Pair<long, int>>()).ToArray();
    }
    /// <summary>
    /// 辺を追加します
    /// </summary>
    /// <param name="u"></param>
    /// <param name="v"></param>
    /// <param name="weight"></param>
    /// <param name="directed">有向辺か</param>
    public void AddEdge(int u, int v, long weight = 1,bool directed=false)
    {
        edge[u].Add(new Pair<long, int>(weight, v));
        if (!directed)
            edge[v].Add(new Pair<long, int>(weight, u));
    }
    /// <summary>
    /// 木の直径をO(E)で求める
    /// 依存:Pair
    /// </summary>
    /// <param name="edge">辺の集合</param>
    /// <returns></returns>
    public long Diameter()
        => Diameter(Diameter(0).v2).v1;
    //bfsなのはStackOverFlow対策(ACならdfsでもよい)
    private Pair<long, int> Diameter(int st)
    {
        var dist = Enumerable.Repeat(-1L, Count).ToArray();
        dist[st] = 0;
        var que = new Queue<int>();
        que.Enqueue(st);
        var maxj = st;
        while (que.Any())
        {
            var p = que.Dequeue();
            foreach (var e in edge[p])
                if (dist[e.v2] == -1)
                {
                    dist[e.v2] = dist[p] + e.v1;
                    if (dist[maxj] < dist[e.v2]) maxj = e.v2;
                    que.Enqueue(e.v2);
                }
        }
        return new Pair<long, int>(dist[maxj], maxj);
    }

    /// <summary>
    /// オイラーツアー
    /// </summary>
    /// <param name="tree"></param>
    /// <param name="root"></param>
    /// <returns></returns>
    public List<int> EularTour(int root)
    {
        etList = new List<int>(Count * 2);
        EularTour(root, -1);
        return etList;
    }
    private void EularTour(int index, int pa)
    {
        etList.Add(index);
        foreach (var c in edge[index])
            if (c.v2 != pa)
                EularTour(c.v2, index);
        etList.Add(index);
    }
}

public class BIT
{
    //1-indexed
    long[] _item;
    public BIT(int num)
    {
        _item = new long[num + 1];
    }
    public long this[int index]
    {
        get { var s = 0L; for (var i = index; i > 0; i -= i & -i) s += _item[i]; return s; }
    }
    public void add(int index, long value)
    {
        for (var i = index; i < _item.Length; i += i & -i) _item[i] += value;
    }
}

public class Input
{
    public static string read => ReadLine().Trim();
    public static int[] ar => read.Split(' ').Select(int.Parse).ToArray();
    public static int num => ToInt32(read);
    public static long[] arL => read.Split(' ').Select(long.Parse).ToArray();
    public static long numL => ToInt64(read);
    public static T[] create<T>(int n, Func<int, T> f)
        => Enumerable.Repeat(0, n).Select(f).ToArray();
    public static char[][] grid(int h)
        => create(h, _ => read.ToCharArray());
    public static int[] ar1D(int n)
        => create(n, _ => num);
    public static long[] arL1D(int n)
        => create(n, _ => numL);
    public static string[] strs(int n)
        => create(n, _ => read);
    public static int[][] ar2D(int n)
        => create(n, _ => ar);
    public static long[][] arL2D(int n)
        => create(n, _ => arL);
    public static List<T>[] edge<T>(int n)
        => create(n, _ => new List<T>());
    public static T GetValue<T>(string g)
    {
        var t = typeof(T);
        if (t == typeof(int))
            return (T)(object)int.Parse(g);
        if (t == typeof(long))
            return (T)(object)long.Parse(g);
        if (t == typeof(string))
            return (T)(object)g;
        if (t == typeof(char))
            return (T)(object)char.Parse(g);
        if (t == typeof(double))
            return (T)(object)double.Parse(g);
        if (t == typeof(bool))
            return (T)(object)bool.Parse(g);
        return default(T);
    }
    public static void Make<T1, T2>(out T1 v1, out T2 v2)
    {
        v1 = Next<T1>();
        v2 = Next<T2>();
    }
    public static void Make<T1, T2, T3>(out T1 v1, out T2 v2, out T3 v3)
    {
        Make(out v1, out v2);
        v3 = Next<T3>();
    }
    public static void Make<T1, T2, T3, T4>(out T1 v1, out T2 v2, out T3 v3, out T4 v4)
    {
        Make(out v1, out v2, out v3);
        v4 = Next<T4>();
    }
    public static void Make<T1, T2, T3, T4, T5>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5)
    {
        Make(out v1, out v2, out v3, out v4);
        v5 = Next<T5>();
    }
    public static void Make<T1, T2, T3, T4, T5, T6>(out T1 v1, out T2 v2, out T3 v3, out T4 v4, out T5 v5, out T6 v6)
    {
        Make(out v1, out v2, out v3, out v4, out v5);
        v6 = Next<T6>();
    }
    private static Queue<string> sc;
    public static T Next<T>(){ sc = sc ?? new Queue<string>(); if (sc.Count == 0) foreach (var item in read.Split(' ')) sc.Enqueue(item);return GetValue<T>(sc.Dequeue()); }
    public static void Next<T>(ref T val) => val = Next<T>(); 
    public const long Inf = (long)1e18;
    public const double eps = 1e-6;
    public const string Alfa = "abcdefghijklmnopqrstuvwxyz";
    public const int MOD = 1000000007;
}

public class Pair<T1, T2> : IComparable<Pair<T1, T2>>
{
    public T1 v1 { get; set; }
    public T2 v2 { get; set; }
    public Pair() { v1 = Input.Next<T1>(); v2 = Input.Next<T2>(); }
    public Pair(T1 v1, T2 v2)
    { this.v1 = v1; this.v2 = v2; }

    public int CompareTo(Pair<T1, T2> p)
    {
        var c = Comparer<T1>.Default.Compare(v1, p.v1);
        if (c == 0)
            c = Comparer<T2>.Default.Compare(v2, p.v2);
        return c;
    }
    public override string ToString()
        => $"{v1.ToString()} {v2.ToString()}";
    public override bool Equals(object obj)
        => this == (Pair<T1, T2>)obj;
    public override int GetHashCode()
        => v1.GetHashCode() ^ v2.GetHashCode();
    public static bool operator ==(Pair<T1, T2> p1, Pair<T1, T2> p2)
        => p1.CompareTo(p2) == 0;
    public static bool operator !=(Pair<T1, T2> p1, Pair<T1, T2> p2)
        => p1.CompareTo(p2) != 0;
    public static bool operator >(Pair<T1, T2> p1, Pair<T1, T2> p2)
        => p1.CompareTo(p2) == 1;
    public static bool operator >=(Pair<T1, T2> p1, Pair<T1, T2> p2)
        => p1.CompareTo(p2) != -1;
    public static bool operator <(Pair<T1, T2> p1, Pair<T1, T2> p2)
        => p1.CompareTo(p2) == -1;
    public static bool operator <=(Pair<T1, T2> p1, Pair<T1, T2> p2)
        => p1.CompareTo(p2) != 1;
}

public class Pair<T1, T2, T3> : Pair<T1, T2>, IComparable<Pair<T1, T2, T3>>
{
    public T3 v3 { get; set; }
    public Pair() : base() { v3 = Input.Next<T3>(); }
    public Pair(T1 v1, T2 v2, T3 v3) : base(v1, v2)
    { this.v3 = v3; }

    public int CompareTo(Pair<T1, T2, T3> p)
    {
        var c = base.CompareTo(p);
        if (c == 0)
            c = Comparer<T3>.Default.Compare(v3, p.v3);
        return c;
    }
    public override string ToString()
        => $"{base.ToString()} {v3.ToString()}";
}
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