Submission #951147

#	Time	Username	Problem	Language	Result	Execution time	Memory
951147		koukirocks	Colors (BOI20_colors)	C++17	22 / 100	1 ms	500 KiB

Colors

#include <bits/stdc++.h>
#define speed ios_base::sync_with_stdio(0); cin.tie(0)
#define all(x) (x).begin(),(x).end()
#define F first
#define S second
 
using namespace std;
typedef long long ll;
typedef double db;
typedef long double ldb;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
 
const ll MAX=2e5+10,P=998244353;
const ll INF=0x3f3f3f3f,oo=0x3f3f3f3f3f3f3f3f;

int n;

int main() {
	speed;
	cin>>n;
	if (n<=64) {
		int now=1;
		int x;
		cout<<"? 1\n"<<flush;
		cin>>x;
		for (int i=1;i<n;i++) {
			now+=(i&1?1:-1)*(n-i);
			cout<<"? "<<now<<"\n"<<flush;
			cin>>x;
			if (x==0) {
				cout<<"= "<<(n-i+1)<<"\n"<<flush;
				return 0;
			}
		}
		cout<<"= 1\n"<<flush;
	} else if (n<=125) {
		int now=n+1>>1;
		int sml;
		cout<<"? "<<now<<"\n"<<flush;
		cin>>sml;
		cout<<"? 1\n"<<flush;
		cin>>sml;
		if (sml) {
			n=(n+1>>1)-1;
			now=1;
			for (int i=1;i<n;i++) {
				now+=(i&1?1:-1)*(n-i);
				int x;
				cout<<"? "<<now<<"\n"<<flush;
				cin>>x;
				if (x==0) {
					cout<<"= "<<(n-i+1)<<"\n"<<flush;
					return 0;
				}
			}
			cout<<"= 1\n"<<flush;
		} else {
			n=(n+1>>1)-1;
			now=1;
			for (int i=1;i<n;i++) {
				now+=(i&1?1:-1)*(2*n-i+1);
				int x;
				cout<<"? "<<now<<"\n"<<flush;
				cin>>x;
				if (x==0) {
					cout<<"= "<<(2*n-i+2)<<"\n"<<flush;
					return 0;
				}
			}
			cout<<"= "<<n+1<<"\n"<<flush;
		}
	} else if (n<=1000) {
		int k=sqrt(n); //1~k , k+1~2k , ... , k*k+1~n
		int cnt=k+(k*k!=n);
		int now=cnt>>1;
		int x;
		cout<<"? "<<now*k+1<<"\n"<<flush;
		cin>>x;
		int gp=k+1;
		for (int i=1;i<=k;i++) {
			now+=((i&1) xor (cnt%2==0)?1:-1)*i;
			cout<<"? "<<min(now*k+1,n)<<"\n"<<flush;
			cin>>x;
			if (x==1) {
				gp=i;
				break;
			}
		}
//		cout<<gp<<"\n";
		// (gp-1)*k ~ gp*k-1
		now=min(now*k+1,n);
		int dir=0;
		if (now>n/2) dir=1;
		if (gp==k+1) {
			for (int gap=min(gp*k,n)-1;gap>=(gp-1)*k+1;gap--) {
				if (dir) now-=gap;
				else now+=gap;
				dir^=1;
				cout<<"? "<<now<<"\n"<<flush;
				cin>>x;
				if (x==0) {
					cout<<"= "<<gap+1<<"\n"<<flush;
					return 0;
				}
			}
			cout<<"= "<<(gp-1)*k+1<<"\n"<<flush;
		} else {
			for (int gap=min(gp*k-1,n);gap>=(gp-1)*k+1;gap--) {
				if (dir) now-=gap;
				else now+=gap;
				dir^=1;
				cout<<"? "<<now<<"\n"<<flush;
				cin>>x;
				if (x==0) {
					cout<<"= "<<gap+1<<"\n"<<flush;
					return 0;
				}
			}
			cout<<"= "<<(gp-1)*k+1<<"\n"<<flush;
		}
	}
	return 0;
}

Compilation message (stderr)

Colors.cpp: In function 'int main()':
Colors.cpp:38:12: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   38 |   int now=n+1>>1;
      |           ~^~
Colors.cpp:45:8: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   45 |    n=(n+1>>1)-1;
      |       ~^~
Colors.cpp:59:8: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   59 |    n=(n+1>>1)-1;
      |       ~^~

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