Submission #464914

#	Time	Username	Problem	Language	Result	Execution time	Memory
464914		Tsovak	Rack (eJOI19_rack)	C++17	0 / 100	1 ms	204 KiB

rack

// -------------------- Includes -------------------- //
#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <stdio.h>
#include <cstdlib>
#include <stdlib.h>
#include <array>
#include <string>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <math.h>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <bitset>
#include <list>
#include <iterator>
#include <numeric>
#include <complex>
#include <tuple>
#include <utility>
#include <cassert>
#include <assert.h>
#include <climits>
#include <limits.h>
#include <ctime>
#include <time.h>
#include <random>
#include <chrono>
#include <fstream>
using namespace std;

// -------------------- Typedefs -------------------- //

typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ld;

// -------------------- Defines -------------------- //

#define pr pair
#define mpr make_pair
#define ff first
#define ss second

#define mset multiset
#define mmap multimap
#define uset unordered_set
#define umap unordered_map
#define umset unordered_multiset
#define ummap unordered_multimap
#define pqueue priority_queue

#define sz(x) (int)x.size()
#define len(x) (int)x.length()
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define clr(x) x.clear()

#define pf push_front
#define pb push_back
#define popf pop_front
#define popb pop_back
#define ft front
#define bk back

#define lb lower_bound
#define ub upper_bound
#define bs binary_search

// -------------------- Constants -------------------- //

const int MAX = int(1e9 + 5);
const ll MAXL = ll(1e18 + 5);
const ll MOD = ll(1e9 + 7);
const ll MOD2 = ll(998244353);

// -------------------- Functions -------------------- //

void fastio()
{
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	return;
}

void precision(int x)
{
	cout.setf(ios::fixed | ios::showpoint);
	cout.precision(x);
	return;
}

ll gcd(ll a, ll b)
{
	if (a > b) {
		swap(a, b);
	}
	if (a == 0) {
		return b;
	}
	if (a == b) {
		return a;
	}
	return gcd(b % a, a);
}

ll lcm(ll a, ll b)
{
	return a / gcd(a, b) * b;
}

bool is_prime(ll a)
{
	ll i;
	for (i = 2; i * i <= a; i++) {
		if (a % i == 0) {
			return false;
		}
	}
	return true;
}

bool is_square(ll a)
{
	ll b = ll(sqrt(a));
	return (b * b == a);
}

bool is_cube(ll a)
{
	ll b = ll(cbrt(a));
	return (b * b * b == a);
}

int digit_sum(ll a)
{
	int sum = 0;
	while (a) {
		sum += int(a % 10);
		a /= 10;
	}
	return sum;
}

ll binpow(ll a, int b)
{
	ll ans = 1;
	while (b) {
		if ((b & 1) == 1) {
			ans *= a;
		}
		b >>= 1;
		a *= a;
	}
	return ans;
}

ll binpow_by_mod(ll a, ll b, ll mod)
{
	ll ans = 1;
	while (b) {
		if ((b & 1) == 1) {
			ans *= a;
			ans %= mod;
		}
		b >>= 1;
		a *= a;
		a %= mod;
	}
	return ans;
}

ll factorial(int a)
{
	int i;
	ll ans = 1;
	for (i = 2; i <= a; i++) {
		ans *= ll(i);
	}
	return ans;
}

ll factorial_by_mod(int a, ll mod)
{
	int i;
	ll ans = 1;
	for (i = 2; i <= a; i++) {
		ans *= i;
		ans %= mod;
	}
	return ans;
}

// -------------------- Solution -------------------- //

/*const int N = 200005;
int a[N];
int n;*/

void solve()
{
	int i, j;
	int n;
	ll k;
	cin >> n >> k;
	ll l, r, mid;
	ll r1, r2, rem;
	if (k % 2 == 1) {
		r1 = 1;
		r2 = 3;
		l = 1;
		r = binpow_by_mod(2, ll(n) - 1LL, MOD);
		ll x = 4;
		for (i = 1; i < n; i++) {
			if (r < l) {
				r += MOD;
			}
			mid = (l + r) / 2;
			if (k < x) {
				break;
			}
			rem = k % x;
			if (rem == r1) {
				r2 = r1 + x;
				r = mid;
			}
			else {
				r1 = r2;
				r2 += x;
				l = mid + 1;
			}
			l %= MOD;
			r %= MOD;
			x *= 2;
		}
		if (k == r2) {
			cout << (l + r) / 2 + 1 << endl;
		}
		else {
			cout << l << endl;
		}
	}
	else {
		r1 = 2;
		r2 = 0;
		l = binpow_by_mod(2, ll(n) - 1LL, MOD) + 1;
		l %= MOD;
		r = binpow_by_mod(2, ll(n), MOD);
		ll x = 4;
		for (i = 1; i < n; i++) {
			if (r < l) {
				r += MOD;
			}
			mid = (l + r) / 2;
			if (k < x) {
				break;
			}
			rem = k % x;
			if (rem == r1) {
				r2 = r1 + x;
				r = mid;
			}
			else {
				r1 = r2;
				r2 += x;
				l = mid + 1;
			}
			l %= MOD;
			r %= MOD;
			x *= 2;
		}
		if (k == r2) {
			cout << (l + r) / 2 + 1 << endl;
		}
		else {
			cout << l << endl;
		}
	}
	return;
}

void precalc()
{
	return;
}

int main()
{
	fastio();

	precalc();

	int tests = 1, tc;
	//cin >> tests;
	for (tc = 1; tc <= tests; tc++) {
		solve();
	}

	//cout << db(clock()) / CLOCKS_PER_SEC << endl;

	return 0;
}

/*
	# # # #   # # # #   # # # #   #       #    #       #     #
	   #      #         #     #    #     #    # #      #   #
	   #      # # # #   #     #     #   #    #   #     # #
	   #            #   #     #      # #    # # # #    #   #
	   #      # # # #   # # # #       #    #       #   #     #
*/

Compilation message (stderr)

rack.cpp: In function 'void solve()':
rack.cpp:213:9: warning: unused variable 'j' [-Wunused-variable]
  213 |  int i, j;
      |         ^

• Subtask 1: 0 / 20
• Subtask 2: 0 / 20
• Subtask 3: 0 / 60