Submission #989567

---

Source Code Expand

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Threading;

using Pair = System.Collections.Generic.KeyValuePair<int, int>;

class Program
{
	public Program() { }

	static void Main(string[] args)
	{
		new Program().prog();
	}
	Scanner cin;
	const int MOD = 1000000007;
	const int INF = int.MaxValue - 10;
	const long INFL = long.MaxValue - 10;
	const double EPS = 1e-7;
	const double PI = 3.1415926536;

	int N;
	List<int>[] G;

	int[] vs, depth, id;
	int root = 0;
	SegTreeMinIndex seg;

	void prog()
	{
		cin = new Scanner();
		int[,] dir8 = new int[8, 2] { { -1, -1 }, { -1, 0 }, { -1, 1 }, { 0, -1 }, { 0, 1 }, { 1, -1 }, { 1, 0 }, { 1, 1 } };
		int[,] dir4 = new int[4, 2] { { -1, 0 }, { 0, -1 }, { 0, 1 }, { 1, 0 } };

		N = cin.nextInt();
		G = new List<int>[N];
		for (int i = 0; i < N; i++)
		{
			G[i] = new List<int>();
		}
		for (int i = 0; i < N-1; i++)
		{
			int x = cin.nextInt() - 1;
			int y = cin.nextInt() - 1;
			G[x].Add(y);
			G[y].Add(x);
		}
		vs = new int[2 * N - 1];
		depth = new int[2 * N - 1];
		id = new int[N];

		init();

		int[] depth_id = new int[N];
		for (int i = 0; i < 2*N-1; i++)
		{
			depth_id[vs[i]] = depth[i];
		}
		
		int Q = cin.nextInt();
		for (int i = 0; i < Q; i++)
		{
			int a = cin.nextInt() - 1;
			int b = cin.nextInt() - 1;
			int c = lca(a, b);
			Console.WriteLine(depth_id[a] + depth_id[b] - 2 * depth_id[c] + 1);
		}
	}

	void dfs(int v, int parent, int d, ref int k)
	{
		id[v] = k;
		vs[k] = v;
		depth[k++] = d;
		for (int i = 0; i < G[v].Count; i++)
		{
			if (G[v][i] != parent)
			{
				dfs(G[v][i], v, d + 1, ref k);
				vs[k] = v;
				depth[k++] = d;
			}
		}
	}

	// 初期化
	void init()
	{
		int k = 0;
		dfs(root, -1, 0, ref k);
		// RMQを初期化する（最小値ではなく、最小値のインデックスを返すようにする）
		seg = new SegTreeMinIndex(depth);
	}

	int lca(int u, int v)
	{
		return vs[seg.rmq(Math.Min(id[u], id[v]), Math.Max(id[u], id[v]) + 1)];
	}

	class SegTreeMinIndex
	{
		int n;  // 葉ノードの数
		int[] dat;
		int[] minIndex;

		// 区間[a,b)の最小値。ノードk=[l,r)に着目している。
		public Pair _rmq(int a, int b, int k, int l, int r)
		{
			if (r <= a || b <= l) return new Pair(INF, -1); // 交差しない
			if (a <= l && r <= b) return new Pair(dat[k], minIndex[k]);    //a,l,r,bの順 
			else {
				Pair s1 = _rmq(a, b, 2 * k + 1, l, (l + r) / 2);
				Pair s2 = _rmq(a, b, 2 * k + 2, (l + r) / 2, r);
				if (s1.Key < s2.Key)
				{
					return s1;
				}
				else
				{
					return s2;
				}
			}
		}

		public int rmq(int a, int b)
		{
			return _rmq(a, b, 0, 0, n).Value;
		}

		public void update(int k, int x)
		{
			k += n - 1;
			dat[k] = x;
			while (k > 0)
			{
				k = (k - 1) / 2;
				if (dat[k * 2 + 1] < dat[k * 2 + 2])
				{
					dat[k] = dat[k * 2 + 1];
					minIndex[k] = minIndex[k * 2 + 1];
				}
				else
				{
					dat[k] = dat[k * 2 + 2];
					minIndex[k] = minIndex[k * 2 + 2];
				}
			}
		}

		public SegTreeMinIndex(int size)
		{
			n = 1;
			while (n < size) n <<= 1;
			dat = new int[2 * n - 1];
			minIndex = new int[2 * n - 1];
		}

		public SegTreeMinIndex(int[] array)
		{
			n = 1;
			while (n < array.Length) n <<= 1;

			dat = new int[2 * n - 1];
			minIndex = new int[2 * n - 1];

			for (int i = 0; i < array.Length; i++)
			{
				dat[i + n - 1] = array[i];
				minIndex[i + n - 1] = i;
			}
			for (int i = array.Length; i < n; i++)
			{
				dat[i + n - 1] = INF;
				minIndex[i + n - 1] = i;
			}
			for (int i = n - 2; i >= 0; i--)
			{
				if (dat[i * 2 + 1] < dat[i * 2 + 2])
				{
					dat[i] = dat[i * 2 + 1];
					minIndex[i] = minIndex[i * 2 + 1];
				}
				else
				{
					dat[i] = dat[i * 2 + 2];
					minIndex[i] = minIndex[i * 2 + 2];
				}
			}
		}
	}
}

class Scanner
{
	string[] s;
	int i;

	char[] cs = new char[] { ' ' };

	public Scanner()
	{
		s = new string[0];
		i = 0;
	}

	public string next()
	{
		if (i < s.Length) return s[i++];
		string st = Console.ReadLine();
		while (st == "") st = Console.ReadLine();
		s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
		i = 0;
		return next();
	}

	public int nextInt()
	{
		return int.Parse(next());
	}

	public long nextLong()
	{
		return long.Parse(next());
	}

	public double nextDouble()
	{
		return double.Parse(next());
	}
}

Submission Info

Judge Result