Submission #1443107

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Source Code Expand

#include<bits/stdc++.h>
using namespace std;
int a,b,n,i,p,q,r,j;
char c;
bool used[2222],ans[2222];
int main()
{
	fflush(stdout);
	srand(time(0));
	cin>>a>>b;
	n=a+b;
	if (a<=b)
	{
		cout<<"Impossible"<<endl;
		return 0;
	}
	p=sqrt(n);
	q=n/p;
	p++;
	for (i=1;i<=p;i++)
	{
		r=rand()%n;
		while(used[r]) r=rand()%n;
		for (j=1;j<=q;j++)
		{
			cout<<"? "<<r<<" "<<r<<endl;
			cin>>c;
			if (c=='N') break;
		}
		used[r]=1;
		if (j>q) 
		{
			ans[r]=1;
			break;
		}
	}
	for (int i=0;i<n;i++)
	{
		if (!used[i])
		{
			cout<<"? "<<r<<" "<<i<<endl;
			cin>>c;
			if (c=='Y') ans[i]=1;
		}
	}
	cout<<"! ";
	for (int i=0;i<n;i++)
	{
		if (ans[i]) cout<<1;
		else cout<<0;
	}
	return 0;
}

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