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.

HackerEarth Monk and Otakuland problem solution


HackerEarth Monk and Otakuland problem solution.

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); }
}

Second solution

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cctype>
#include<cstdlib>
#include<algorithm>
#include<bitset>
#include<vector>
#include<list>
#include<deque>
#include<queue>
#include<map>
#include<set>
#include<stack>
#include<cmath>
#include<sstream>
#include<fstream>
#include<iomanip>
#include<ctime>
#include<complex>
#include<functional>
#include<climits>
#include<cassert>
#include<iterator>
#include<unordered_map>
#include<unordered_set>
//#include<quadmath.h>
using namespace std;

namespace test{
void end_test(){
int val;
if (cin >> val){
exit(1);
}
}
void range_test(int t, int l, int r){
if (t < l || r < t){
exit(1);
}
}
}
struct st{
int countt;
int countt1;
int rev;
st(){
countt = countt1 = 0;
rev = 0;
}
};
#define MAX 200000
st seg[MAX * 4];
void update(int b){
seg[b].rev %= 2;
if (seg[b].rev){
swap(seg[b].countt, seg[b].countt1);
}
if (b * 2 + 2 < MAX * 4){
seg[b * 2 + 1].rev += seg[b].rev;
seg[b * 2 + 2].rev += seg[b].rev;
}
seg[b].rev = 0;
}
st merge(st a, st b){
st r;
r.countt = a.countt + b.countt;
r.countt1 = a.countt1 + b.countt1;
return r;
}
st emp;
inline st q(int b, int l, int r, int ll, int rr){
update(b);
if (ll <= l&&r <= rr){
return seg[b];
}
if (r <= ll || rr <= l){
return emp;
}
return merge(q(b * 2 + 1, l, (l + r) >> 1, ll, rr), q(b * 2 + 2, (l + r) >> 1, r, ll, rr));
}
inline void add(int b, int l, int r, int ll, int rr){
update(b);
if (ll <= l&&r <= rr){
seg[b].rev++;
update(b);
return;
}
if (rr <= l || r <= ll){
return;
}
add(b * 2 + 1, l, (l + r) >> 1, ll, rr);
add(b * 2 + 2, (l + r) >> 1, r, ll, rr);
seg[b] = merge(seg[b * 2 + 1], seg[b * 2 + 2]);
}
char a[MAX];
inline void init(int b, int l, int r){
if (l + 1 == r){
if (a[l] == '<'){
seg[b].countt++;
}
else{
seg[b].countt1++;
}
return;
}
init(b * 2 + 1, l, (l + r) >> 1);
init(b * 2 + 2, (l + r) >> 1, r);
seg[b] = merge(seg[b * 2 + 1], seg[b * 2 + 2]);
}
int main(){
int n;
int m;
scanf("%d%d", &n, &m);
test::range_test(n, 2, 200000);
test::range_test(m, 1, 200000);
scanf("%s", a);
init(0, 0, n - 1);
long long int T=0;
while (m--){
int ty;
scanf("%d", &ty);
test::range_test(ty, 1, 2);
if (ty == 1){
int l, r;
scanf("%d%d", &l, &r);
test::range_test(l, 1, n);
test::range_test(r, 1, n);
l--;
r--;
add(0, 0, n - 1, l, r);
continue;
}
int f, t;
scanf("%d%d", &f, &t);
T+=(long long int)(abs(f-t));
test::range_test(1, 1, n);
test::range_test(1, 1, n);
f--;
t--;
if (f == t){
puts("0");
continue;
}
int l = min(f, t);
int r = max(f, t);
st ans = q(0, 0, n - 1, l, r);
if (f > t){
printf("%d\n", ans.countt1);
}
else{
printf("%d\n", ans.countt);
}
}
test::end_test();
/*if(T<100000000){
exit(1); //brute-force solution
}*/
return 0;
}