We're no strangers to love
You know the rules and so do I
A full commitment's what I'm thinking of
You wouldn't get this from any other guy
I just wanna tell you how I'm feeling
Gotta make you understand
Never gonna give you up
Never gonna let you down
Never gonna run around and desert you
Never gonna make you cry
Never gonna say goodbye
Never gonna tell a lie and hurt you
We've known each other for so long
Your heart's been aching but you're too shy to say it
Inside we both know what's been going on
We know the game and we're gonna play it
And if you ask me how I'm feeling
Don't tell me you're too blind to see
Never gonna give you up
Never gonna let you down
Never gonna run around and desert you
Never gonna make you cry
Never gonna say goodbye
Never gonna tell a lie and hurt you
Never gonna give you up
Never gonna let you down
Never gonna run around and desert you
Never gonna make you cry
Never gonna say goodbye
Never gonna tell a lie and hurt you
(Ooh give you up)
(Ooh give you up)
(Ooh) never gonna give, never gonna give
(give you up)
(Ooh) never gonna give, never gonna give
(give you up)
We've known each other for so long
Your heart's been aching but you're too shy to say it
Inside we both know what's been going on
We know the game and we're gonna play it
I just wanna tell you how I'm feeling
Gotta make you understand
Never gonna give you up
Never gonna let you down
Never gonna run around and desert you
Never gonna make you cry
Never gonna say goodbye
Never gonna tell a lie and hurt you
Never gonna give you up
Never gonna let you down
Never gonna run around and desert you
Never gonna make you cry
Never gonna say goodbye
Never gonna tell a lie and hurt you
Never gonna give you up
Never gonna let you down
Never gonna run around and desert you
Never gonna make you cry
Never gonna say goodbye
Never gonna tell a lie and hurt you

猜數程序（a.cpp）

#include<bits/stdc++.h>
using namespace std;
using llt=long long;
using llf=long double;
using ull=unsigned long long;
#ifdef LOCAL
	FILE *InFile=freopen("in_out/in.in","r",stdin),*OutFile=freopen("in_out/out.out","w",stdout);
#else
	FILE *InFile=stdin,*OutFile=stdout;
#endif

const llt RG=1e18;

int main(){
	ios::sync_with_stdio(false),cin.tie(nullptr),cout.tie(nullptr);
	llt l=1,r=RG;
	while(l<=r){
		llt mid=(l+r)>>1; bool fg; cout<<"? "<<mid<<endl,cin>>fg;
		if(fg) r=mid-1;
		else l=mid+1;
	}
	cout<<"! "<<l<<endl;
}

交互程序（b.cpp）

#include<bits/stdc++.h>
using namespace std;
using llt=long long;
using llf=long double;
using ull=unsigned long long;
#ifdef LOCAL
	FILE *InFile=freopen("in_out/in.in","r",stdin),*OutFile=freopen("in_out/out.out","w",stdout);
#else
	FILE *InFile=stdin,*OutFile=stdout;
#endif

const llt RG=1e18;
mt19937_64 rnd(ull(new char)*ull(new char));
 
int main(){
	ios::sync_with_stdio(false),cin.tie(nullptr),cout.tie(nullptr);
    llt a=rnd()%RG+1,tot=0;
	while(true){
		char k; llt x; cin>>k>>x;
		if(k=='?') cout<<(x>=a)<<endl,++tot;
		else{
			if(x!=a) return cerr<<"Sorry, you are wrong. Answer: "<<a<<' '<<x<<endl,-1;
			else return cerr<<"Good, you are right. Times: "<<tot<<endl,0;
		}
	}
}

Run 記得先用 mkfifo 建 inpipe 和 outpipe

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

int main(){
	assert(!system("g++ a.cpp -o a -O2 -std=c++14"));
	assert(!system("g++ b.cpp -o b -O2 -std=c++14"));
    system("(./a>inpipe<outpipe)&(./b<inpipe>outpipe)");
}

注意要把先輸出的放到前面