Submission #3552807

---

Source Code Expand

#include<bits/stdc++.h>
#define debug(x) cerr<<#x<<" = "<<x
#define sp <<"  "
#define el <<endl
#define LL long long
#define M 100020
using namespace std;
namespace IO{
	const int BS=(1<<20)+5; int Top=0;
	char Buffer[BS],OT[BS],*OS=OT,*HD,*TL,SS[20]; const char *fin=OT+BS-1;
	char Getchar(){if(HD==TL){TL=(HD=Buffer)+fread(Buffer,1,BS,stdin);} return (HD==TL)?EOF:*HD++;}
	void flush(){fwrite(OT,1,OS-OT,stdout);}
	void Putchar(char c){*OS++ =c;if(OS==fin)flush(),OS=OT;}
	void write(int x){
		if(!x){Putchar('0');return;} if(x<0) x=-x,Putchar('-');
		while(x) SS[++Top]=x%10,x/=10;
		while(Top) Putchar(SS[Top]+'0'),--Top;
	}
	int read(){
		int nm=0,fh=1; char cw=getchar();
		for(;!isdigit(cw);cw=getchar()) if(cw=='-') fh=-fh;
		for(;isdigit(cw);cw=getchar()) nm=nm*10+(cw-'0');
		return nm*fh;
	}
}
using namespace IO;
int A,B,n,top,last,S[M],now; char res; bool vis[M];
bool ask(int x,int y){cout<<"? "<<x-1<<" "<<y-1<<endl;cin>>res; return res=='Y';}
int main(){
	//freopen(".in","r",stdin);
	//freopen(".out","w",stdout);
	cin>>A>>B; n=A+B; S[top=1]=n;
	if(A<=B){cout<<"Impossible"<<endl;return 0;}
	for(int k=1,cnt=0;k<n;k++){
		if(!top){S[top=1]=k;continue;}
		if(!ask(S[top],k)) top--;else S[++top]=k;
	}now=S[top];
	for(int i=1;i<=n;i++) vis[i]=ask(now,i); cout<<"! "; 
	for(int i=1;i<=n;i++) cout<<vis[i]; cout<<endl;
	return 0;
}

Submission Info

Judge Result