Submission #299571

#	Time	Username	Problem	Language	Result	Execution time	Memory
299571		E869120	Colors (BOI20_colors)	C++14	67 / 100	1 ms	512 KiB

Colors

#include <bits/stdc++.h>
using namespace std;

int Debug = 1;
long long N;
long long C = 38;
long long prevs = 0;

int getans(long long pos) {
	cout << "? " << pos << endl;
	if (Debug == 1) {
		int x;
		cin >> x;
		return x;
	}
	if (Debug == 2) {
		int x = -1;
		if (abs(prevs - pos) < C) x = 0;
		else x = 1;
		prevs = pos;
		return x;
	}
	return -1;
}

void solves() {
	// Step #1. Input
	cin >> N;
	if (N == 1) {
		cout << "= 1" << endl;
		return;
	}
	
	// Step #2. Get Answer
	long long cl = 1, cr = (N / 2) + 1, cm, minx = N;
	long long pre = -1;
	map<long long, int> Map;
	map<long long, int> Map2;
	
	for (int i = 0; i < 100; i++) {
		cm = (cl + cr) / 2; if (Map[cm] == 1) break;
		Map[cm] = 1;
		int z1 = getans(cm); Map2[cm] = 1;
		if (pre != -1LL && z1 == 1) minx = min(minx, abs(pre - cm));
		pre = cm;
		int z2 = getans(N + 1LL - cm); Map2[N + 1LL - cm] = 1;
		if (pre != -1LL && z2 == 1) minx = min(minx, abs(pre - (N + 1LL - cm)));
		pre = N + 1LL - cm;
		if (z2 == 1) { cl = cm; }
		else { cr = cm; }
	}
	
	// Step #3. Baaiwake
	if (N % 2LL == 1LL) {
		int z3 = getans(N / 2LL + 1LL);
		if (pre != -1LL && z3 == 1) minx = min(minx, abs(pre - (N / 2LL + 1LL)));
		Map2[N / 2LL + 1LL] = 1;
	}
	
	// Step #4. Baaiwake 2
	if (minx >= 2LL) {
		long long target = minx - 1;
		for (int i = 1; i <= N - target; i++) {
			if (Map2[i] == 0 && Map2[i + target] == 0) {
				Map2[i] = 1;
				Map2[i + target] = 1;
				int z1 = getans(i);
				int z2 = getans(i + target);
				if (z2 == 1) minx = min(minx, target);
				break;
			}
		}
	}
	
	// Step #5. Get Answer
	cout << "= " << minx << endl;
	return;
}

int main() {
	solves();
	return 0;
}

Compilation message (stderr)

Colors.cpp: In function 'void solves()':
Colors.cpp:67:9: warning: unused variable 'z1' [-Wunused-variable]
   67 |     int z1 = getans(i);
      |         ^~

• Subtask 1: 9 / 9
• Subtask 2: 13 / 13
• Subtask 3: 21 / 21
• Subtask 4: 24 / 24
• Subtask 5: 0 / 33