Submission #871405

#	Time	Username	Problem	Language	Result	Execution time	Memory
871405		rainboy	Secret Permutation (RMI19_permutation)	C++17	93.33 / 100	8 ms	688 KiB

permutation

#include "permutation.h"
#include <cstring>
#include <vector>

using namespace std;

typedef vector<int> vi;

const int N = 256;

int abs_(int a) { return a > 0 ? a : -a; }
int min(int a, int b) { return a < b ? a : b; }
int max(int a, int b) { return a > b ? a : b; }

unsigned int X = 12345;

int rand_() {
	return (X *= 3) >> 1;
}

char used[N];

int check(int *pp, int n, int m) {
	int p = 0;
	for (int i = 0; i < m; i++)
		p = min(p, pp[i]);
	memset(used, 0, n * sizeof *used);
	for (int i = 0; i < m; i++) {
		if (pp[i] - p >= n || used[pp[i] - p])
			return 0;
		used[pp[i] - p] = 1;
	}
	return 1;
}

int rr[N], dd[N], ppp[N + 1][N], ppp_[N + 1][N], m, m_;

void solve(int n) {
	for (int i = 0; i < n; i++)
		rr[i] = i;
	for (int i = 0; i < n; i++) {
		int j = rand_() % (i + 1), tmp;
		tmp = rr[i], rr[i] = rr[j], rr[j] = tmp;
	}
	vi ii(n);
	for (int i = 0; i < n; i++) {
		for (int h = 0; h < n; h++)
			ii[h] = rr[(i + h) % n] + 1;
		dd[i] = query(ii);
	}
	int sum = 0;
	for (int i = 0; i < n; i++)
		sum += dd[i];
	sum /= (n - 1);
	for (int i = 0; i < n; i++)
		dd[i] = sum - dd[i];
	vi pp(n), qq(n);
	pp[0] = 0, pp[1] = dd[1];
	for (int i = 2; i < n; i++) {
		int m = 0;
		for (int j = 0; j < i; j++)
			ppp[m][j] = pp[j];
		m++;
		while (i < n) {
			m_ = 0;
			for (int h = 0; h < m; h++) {
				memcpy(ppp_[m_], ppp[h], i * sizeof *ppp[h]), ppp_[m_][i] = ppp[h][i - 1] + dd[i];
				if (check(ppp_[m_], n, i + 1))
					m_++;
				if (m_ > n)
					break;
				memcpy(ppp_[m_], ppp[h], i * sizeof *ppp[h]), ppp_[m_][i] = ppp[h][i - 1] - dd[i];
				if (check(ppp_[m_], n, i + 1))
					m_++;
				if (m_ > n)
					break;
			}
			memset(used, 0, n * sizeof *used);
			for (int h = 0; h < m_; h++) {
				int p = abs_(ppp_[h][i]);
				if (used[p])
					goto out;
				used[p] = 1;
			}
			m = m_;
			for (int h = 0; h < m_; h++)
				memcpy(ppp[h], ppp_[h], (i + 1) * sizeof *ppp_[h]);
			i++;
		}
out:
		if (i == n) {
			for (int h = 0; h < m; h++)
				if (abs_(ppp[h][0] - ppp[h][n - 1]) == dd[0]) {
					for (int j = 0; j < n; j++)
						pp[j] = ppp[h][j];
					break;
				}
		} else {
			i--;
			for (int h = 0; h < n; h++)
				ii[h] = rr[h < i ? i - 1 - h : h] + 1;
			int p = query(ii) - (sum - dd[0]) + dd[i];
			for (int h = 0; h < m; h++)
				if (abs_(ppp[h][i]) == p) {
					for (int j = 0; j <= i; j++)
						pp[j] = ppp[h][j];
					break;
				}
		}
	}
	int p = 0;
	for (int i = 0; i < n; i++)
		p = min(p, pp[i]);
	for (int i = 0; i < n; i++)
		pp[i] -= p - 1;
	for (int i = 0; i < n; i++)
		qq[rr[i]] = pp[i];
	for (int i = 0; i < n; i++)
		pp[i] = qq[i];
	answer(pp);
}

Compilation message (stderr)

stub.cpp: In function 'int query(int*)':
stub.cpp:15:9: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   15 |   fscanf(stdin, "%d", &x);
      |   ~~~~~~^~~~~~~~~~~~~~~~~
stub.cpp: In function 'int main(int, char**)':
stub.cpp:48:9: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   48 |   fscanf(stdin, "%d", &N);
      |   ~~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 13.999995 / 15
• Subtask 2: 32.666655 / 35
• Subtask 3: 46.66665 / 50