HackerEarth Monk and Otakuland problem solution

In this HackerEarth Monk and Otakuland problem Monk lives in Otakuland. Otakuland consists of N vertices and N-1 directed edges. i-th edge is a directed edge either from i-th vertex to i+1-th vertex or from i+1-th vertex to i-th vertex. You are given M Queries. Queries are 2 types:

1. r – Reverse the direction of the edges between l-th vertex and r-th vertex.
2. f t – Output the minimum number of edges which you have to reverse the direction to arrive from f to t.

using System;
using System.Linq;
using System.Diagnostics;
using System.Collections.Generic;
using Debug = System.Diagnostics.Debug;
using StringBuilder = System.Text.StringBuilder;
using System.Numerics;

namespace Program
{

    public class Solver
    {
        public void Solve()
        {
            var n = sc.Integer();
            var m = sc.Integer();
            var s = sc.Scan();
            var seg = new LazyEvaluateDirectionTree(n - 1);
            for (int i = 0; i < n - 1; i++)
            {
                if (s[i] == '<')
                    seg.Reverse(i, i + 1);
            }
            for (int i = 0; i < m; i++)
            {
                var t = sc.Integer();
                var l = sc.Integer() - 1;
                var r = sc.Integer() - 1;
                if (t == 1)
                {
                    seg.Reverse(l, r);
                }
                else
                {
                    var rev = false;
                    if (l > r) { rev = true; Swap(ref l, ref r); }
                    var ret = seg.Query(l, r);
                    var ans = rev ? ret.x : ret.y;
                    IO.Printer.Out.WriteLine(ans);
                }
            }
        }
        public IO.StreamScanner sc = new IO.StreamScanner(Console.OpenStandardInput());
        static T[] Enumerate<T>(int n, Func<int, T> f) { var a = new T[n]; for (int i = 0; i < n; ++i) a[i] = f(i); return a; }
        static public void Swap<T>(ref T a, ref T b) { var tmp = a; a = b; b = tmp; }
    }

}

#region main
static class Ex
{
    static public string AsString(this IEnumerable<char> ie) { return new string(System.Linq.Enumerable.ToArray(ie)); }
    static public string AsJoinedString<T>(this IEnumerable<T> ie, string st = " ") { return string.Join(st, ie); }
    static public void Main()
    {
        var solver = new Program.Solver();
        solver.Solve();
        Program.IO.Printer.Out.Flush();
    }
}
#endregion
#region Ex
namespace Program.IO
{
    using System.IO;
    using System.Text;
    using System.Globalization;
    public class Printer : StreamWriter
    {
        static Printer() { Out = new Printer(Console.OpenStandardOutput()) { AutoFlush = false }; }
        public static Printer Out { get; set; }
        public override IFormatProvider FormatProvider { get { return CultureInfo.InvariantCulture; } }
        public Printer(System.IO.Stream stream) : base(stream, new UTF8Encoding(false, true)) { }
        public Printer(System.IO.Stream stream, Encoding encoding) : base(stream, encoding) { }
        public void Write<T>(string format, T[] source) { base.Write(format, source.OfType<object>().ToArray()); }
        public void WriteLine<T>(string format, T[] source) { base.WriteLine(format, source.OfType<object>().ToArray()); }
    }
    public class StreamScanner
    {
        public StreamScanner(Stream stream) { str = stream; }
        public readonly Stream str;
        private readonly byte[] buf = new byte[1024];
        private int len, ptr;
        public bool isEof = false;
        public bool IsEndOfStream { get { return isEof; } }
        private byte read()
        {
            if (isEof) return 0;
            if (ptr >= len) { ptr = 0; if ((len = str.Read(buf, 0, 1024)) <= 0) { isEof = true; return 0; } }
            return buf[ptr++];
        }
        public char Char() { byte b = 0; do b = read(); while ((b < 33 || 126 < b) && !isEof); return (char)b; }

        public string Scan()
        {
            var sb = new StringBuilder();
            for (var b = Char(); b >= 33 && b <= 126; b = (char)read())
                sb.Append(b);
            return sb.ToString();
        }
        public string ScanLine()
        {
            var sb = new StringBuilder();
            for (var b = Char(); b != 'n'; b = (char)read())
                if (b == 0) break;
                else if (b != 'r') sb.Append(b);
            return sb.ToString();
        }
        public long Long()
        {
            if (isEof) return long.MinValue;
            long ret = 0; byte b = 0; var ng = false;
            do b = read();
            while (b != 0 && b != '-' && (b < '0' || '9' < b));
            if (b == 0) return long.MinValue;
            if (b == '-') { ng = true; b = read(); }
            for (; true; b = read())
            {
                if (b < '0' || '9' < b)
                    return ng ? -ret : ret;
                else ret = ret * 10 + b - '0';
            }
        }
        public int Integer() { return (isEof) ? int.MinValue : (int)Long(); }
        public double Double() { var s = Scan(); return s != "" ? double.Parse(Scan(), CultureInfo.InvariantCulture) : double.NaN; }
        private T[] enumerate<T>(int n, Func<T> f)
        {
            var a = new T[n];
            for (int i = 0; i < n; ++i) a[i] = f();
            return a;
        }

        public char[] Char(int n) { return enumerate(n, Char); }
        public string[] Scan(int n) { return enumerate(n, Scan); }
        public double[] Double(int n) { return enumerate(n, Double); }
        public int[] Integer(int n) { return enumerate(n, Integer); }
        public long[] Long(int n) { return enumerate(n, Long); }
    }
}
#endregion

#region LazyEvalDirection
public class LazyEvaluateDirectionTree
{
    static readonly Pair<int, int> ZERO = Pair.Create(0, 0);
    int n;
    Pair<int, int>[] data;
    bool[] rev;
    public LazyEvaluateDirectionTree(int size)
    {
        n = 1;
        while (n < size)
            n <<= 1;
        data = new Pair<int, int>[n << 1];
        rev = new bool[n << 1];
        for (int i = 0; i < size; i++)
            data[i + n] = Pair.Create(1, 0);
        for (int i = n - 1; i >0; i--)
        {
            eval(i);
        }

    }
    private void lazyEval(int k, int a, int b)
    {
        if (!rev[k])
            return;
        Reverse(a, (a + b) >> 1, k << 1, a, (a + b) >> 1);
        Reverse((a + b) >> 1, b, (k << 1) + 1, (a + b) >> 1, b);
        rev[k] = false;
    }
    private void eval(int k)
    {
        int l = k << 1, r = (k << 1) + 1;
        data[k] = Pair.Create(data[l].x + data[r].x, data[l].y + data[r].y);
    }
    public void Reverse(int a, int b)
    {
        Reverse(a, b, 1, 0, n);
    }
    private void Reverse(int a, int b, int k, int l, int r)
    {
        if (r <= a || b <= l)
            return;
        else if (a <= l && r <= b)
        {
            rev[k] = !rev[k];
            Swap(ref data[k].x, ref data[k].y);
        }
        else
        {
            lazyEval(k, l, r);
            Reverse(a, b, k << 1, l, (l + r) >> 1);
            Reverse(a, b, (k << 1) + 1, (l + r) >> 1, r);
            eval(k);
        }
    }
    public Pair<int, int> Query(int a, int b) { return Query(a, b, 1, 0, n); }
    private Pair<int, int> Query(int a, int b, int k, int l, int r)
    {
        if (r <= a || b <= l)
            return ZERO;
        if (a <= l && r <= b)
            return data[k];
        else
        {
            lazyEval(k, l, r);
            var vl = Query(a, b, k << 1, l, (l + r) >> 1);
            var vr = Query(a, b, (k << 1) + 1, (l + r) >> 1, r);
            eval(k);
            return Pair.Create(vl.x + vr.x, vl.y + vr.y);
        }
    }
    static public void Swap<T>(ref T a, ref T b) { var tmp = a; a = b; b = tmp; }

}
#endregion

#region Compair
static public class Pair
{
    static public Pair<FT, ST> Create<FT, ST>(FT f, ST s)
        where FT : IComparable<FT>
        where ST : IComparable<ST>
    { return new Pair<FT, ST>(f, s); }
    static public Pair<FT, ST> Min<FT, ST>(Pair<FT, ST> p, Pair<FT, ST> q)
        where FT : IComparable<FT>
        where ST : IComparable<ST>
    { return (p.CompareTo(q) <= 0) ? p : q; }
    static public Pair<FT, ST> Max<FT, ST>(Pair<FT, ST> p, Pair<FT, ST> q)
        where FT : IComparable<FT>
        where ST : IComparable<ST>
    { return (p.CompareTo(q) >= 0) ? p : q; }
}
public struct Pair<FT, ST> : IComparable<Pair<FT, ST>>
    where FT : IComparable<FT>
    where ST : IComparable<ST>
{
    public FT x;
    public ST y;
    public Pair(FT f, ST s) : this() { x = f; y = s; }

    public int CompareTo(Pair<FT, ST> other)
    {
        var cmp = x.CompareTo(other.x);
        return cmp != 0 ? cmp : y.CompareTo(other.y);
    }
    public override string ToString() { return string.Format("{0} {1}", x, y); }
}