Submission #1152957

#	Time	Username	Problem	Language	Result	Execution time	Memory
1152957		MinhTuan11	Colors (BOI20_colors)	C++20	100 / 100	1 ms	436 KiB

Colors

#include <bits/stdc++.h>

#define int long long
#define fi first
#define se second

const int N = 2e5 + 5;
const int K = 1e2 + 5;
const int mod = 1e9 + 7;
const int inf = 1e18 + 7;

#define all(v) (v).begin(), (v).end()
#define pii pair<int, int>

using namespace std;

mt19937 rd(chrono::steady_clock::now().time_since_epoch().count());

int n;
vector<int> m;

int ask(int ques) {
	cout << "? " << ques << endl;
	int rep;
	cin >> rep;
	return rep;
}

void prep() {
	int l = 0, r = n;
	while(l < r - 1) {
		int mid = (l + r) / 2;
		m.push_back(mid);
		l = mid;
	}
}

void solve() {
	int mini = 0, maxi = 0, cur = 0;
	for(int i = 0; i < m.size(); i++) {
		if(i & 1LL) cur -= m[i];
		else cur += m[i];
		mini = min(mini, cur);
		maxi = max(maxi, cur);
	}
	if(maxi + (- mini) >= n) {
		assert(1 == 2);
	}
	else {
		int pos = - mini + 1, query = 1;
		int rep = ask(pos);
		int l = 0, r = n, mid;
		while(l < r - 1) {
			mid = (l + r) / 2;
			if(query & 1LL) {
				pos += mid;
			}
			else {
				pos -= mid;
			}
			++query;
			rep = ask(pos);
			if(rep) r = mid;
			else l = mid;
		}
		cout << "= " << r << endl;
	}
}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    if(ifstream("file.inp")){
    	freopen("file.inp", "r", stdin);
    	freopen("file.out", "w", stdout);
    }

    cin >> n;
    prep();
    solve();

    return 0;
}

// tuntun

Compilation message (stderr)

Colors.cpp: In function 'int main()':
Colors.cpp:75:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   75 |         freopen("file.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Colors.cpp:76:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   76 |         freopen("file.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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