Submission #236296

#	Time	Username	Problem	Language	Result	Execution time	Memory
236296		tjd229	Secret Permutation (RMI19_permutation)	C++14	50 / 100	5048 ms	384 KiB

permutation

#include  "permutation.h"
#include <vector>
#include <algorithm>
#include <random>
using namespace std;
 
 
int Tx[257], x[257];
int use[257];
int _N;
#include <stdio.h>
void print(int *p) {
	for (int i = 1; i <= _N; ++i) printf("%d ", p[i]);
	puts("");
}
bool recon(int ix, vector<int> &P) {
 
	int bk = P.back();
	//
	if (ix == _N) {
		int d = bk - P[0];
		if (d < 0) d = -d;
		return d == x[1];
	}
	int nxt = bk + x[ix + 1];
	if (nxt <= _N && use[nxt] == 0) {
		use[nxt] = 1;
		P.push_back(nxt);
		if (recon(ix + 1, P)) return 1;
		P.pop_back();
		use[nxt] = 0;
	}
	nxt = bk - x[ix + 1];
	if (nxt > 0 && use[nxt] == 0) {
		use[nxt] = 1;
		P.push_back(nxt);
		if (recon(ix + 1, P)) return 1;
		P.pop_back();
		use[nxt] = 0;
	}
	return 0;
}
void solve(int N) {
	_N = N;
	int sum = 0;
	vector<int> P, V;
	for (int i = 1; i <= N; ++i) V.push_back(i);
	/*mt19937 g(random_device);
	shuffle(V.begin(), V.end(),g);*/
	//srand(229);
	random_shuffle(V.begin(), V.end());
 
	for (int i = 1; i <= N; ++i) {
		Tx[i] = query(V);
		sum += Tx[i];
		use[i] = 0;
		rotate(V.begin(), V.begin() + 1, V.end());
	}
	int T = sum / (N - 1);
 
	for (int i = 1; i <= N; ++i) x[i] = T - Tx[i];
	//print(x);
	for (int i = 1; i <= N; ++i) {
      if (i + x[1] > N && i - x[1] < 1) continue;
		P.push_back(i); use[i] = 1;
		if (recon(1, P)) {
			vector<int> ans(N);
			for (i = 0; i < N; ++i)
				ans[V[i] - 1] = P[i];// , printf("%d,%d\n", V[i], P[i]);
 
			answer(ans);
			break;
		}
		P.pop_back(); use[i] = 0;
	}
}

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]
   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]
   fscanf(stdin, "%d", &N);
   ~~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 15 / 15
• Subtask 2: 35 / 35
• Subtask 3: 0 / 50