Submission #810533

#	Time	Username	Problem	Language	Result	Execution time	Memory
810533		ymm	Colors (BOI20_colors)	C++17	9 / 100	1 ms	336 KiB

Colors

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

set<ll> S;
ll n;
bool query(ll x)
{
	assert(0 <= x && x < n && !S.count(x));
	S.insert(x);
	int d;
	printf("? %lld\n", x+1);
	fflush(stdout);
	scanf("%d", &d);
	return d;
}

int main()
{
	scanf("%lld", &n);
	query(0);
	ll ans = 1;
	ll pos = 0;
	for (int i = 0; i < n-1; ++i) {
		ll pos2 = i%2? n-pos: n-1-pos;
		if (!query(pos2)) {
			ans = abs(pos-pos2)+1;
			break;
		}
		pos = pos2;
	}
	printf("= %lld\n", ans);
}

Compilation message (stderr)

Colors.cpp: In function 'bool query(ll)':
Colors.cpp:14:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   14 |  scanf("%d", &d);
      |  ~~~~~^~~~~~~~~~
Colors.cpp: In function 'int main()':
Colors.cpp:20:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   20 |  scanf("%lld", &n);
      |  ~~~~~^~~~~~~~~~~~

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