Submission #467184

#	Time	Username	Problem	Language	Result	Execution time	Memory
467184		nemethm	Rack (eJOI19_rack)	C++17	100 / 100	1 ms	204 KiB

rack

#include <iostream>
#include <list>
#include <algorithm>
#include <queue>
#include <vector>
#include <limits>
#include <set>
#include <numeric>
#include <string>
#include <assert.h>
#include <map>
#include <cmath>
#include <stack>
#include <cstring>
#include <stack>
#pragma warning(disable : 4996)
using namespace std;
using ll = long long int;
const ll inf = numeric_limits<ll>::max();
//const ll mod = 1e9+7;
void setIO(string s) {
	freopen((s + ".in").c_str(), "r", stdin);
	freopen((s + ".out").c_str(), "w", stdout);
}

uint64_t binpow(uint64_t base, uint64_t exp, uint64_t mod) {
	if (exp == 0) return 1;
	uint64_t half = binpow(base, exp / 2, mod);
	uint64_t answ = (half * half) % mod;
	if (exp % 2 == 1) {
		answ *= base;
		answ %= mod;
	}
	return answ;
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.precision(9);
	uint64_t n, k, m = 1e9 + 7;
	cin >> n >> k;
	--k;
	uint64_t k_rev = 0;
	for (int i = 0; i < 64; ++i) {
		if ((k >> i) & 1) k_rev |= 1ull << (64 - i - 1);
	}
	if (n <= 64) {
		k_rev >>= (64 - n);
		k_rev %= m;
		++k_rev;
		k_rev %= m;
		cout << k_rev << endl;
	}
	else {
		uint64_t twopower = binpow(2, n - 64, m);
		uint64_t answ = 0;
		for (int i = 0; i < 64; ++i) {
			if ((k_rev >> i) & 1) {
				answ += twopower;
				answ %= m;
			}
			twopower *= 2;
			twopower %= m;
		}
		++answ;
		answ %= m;
		cout << answ << endl;
	}
	return 0;
}

Compilation message (stderr)

rack.cpp:16: warning: ignoring '#pragma warning ' [-Wunknown-pragmas]
   16 | #pragma warning(disable : 4996)
      | 
rack.cpp: In function 'void setIO(std::string)':
rack.cpp:22:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   22 |  freopen((s + ".in").c_str(), "r", stdin);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
rack.cpp:23:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   23 |  freopen((s + ".out").c_str(), "w", stdout);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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