#include <bits/stdc++.h>
void send_message(std::vector<bool> M, std::vector<bool> C){
	M.push_back(0);
	while(M.size()<1025)M.push_back(1);
	int idx=0;
	std::vector<int> d,pos;
	for(int i=0;i<31;i++)if(!C[i])pos.push_back(i);
	for(int i=0;i<31;i++)d.push_back(0);
	for(int i=0;i<16;i++)d[pos[i]]=(pos[(i+1)%16]-pos[i]+31)%31;
	for(int i=1;i<=66;i++){
		std::vector<bool> res;
		for(int j=0;j<31;j++){
			if(C[j])res.push_back(0);
			else{
				if(i<d[j])res.push_back(0);
				else if(i==d[j])res.push_back(1);
				else res.push_back(M[idx++]);
			}
		}
		send_packet(res);
	}
}
std::vector<bool> receive_message(std::vector<std::vector<bool> > R){
	std::vector<int> d;
	std::vector<bool> st,ok,res;
	for(int i=0;i<31;i++)d.push_back(0),st.push_back(0),ok.push_back(0);
	for(int i=0;i<66;i++)
		for(int j=0;j<31;j++)if(!d[j]&&R[i][j])d[j]=i+1;
	for(int i=0;i<31;i++){
		int cur=i,sum=0;
		while(!st[cur]){
			sum++;
			st[cur]=sum;
			(cur+=d[cur])%=31;
		}
		if(sum-st[cur]+1==16){
			int curcur=(cur+d[cur])%31;
			ok[cur]=1;
			while(curcur!=cur){
				ok[curcur]=1;
				(curcur+=d[curcur])%=31;
			}
			break;
		}
		for(int j=0;j<31;j++)st[j]=0;
	}
	for(int i=0;i<66;i++)
		for(int j=0;j<16;j++)if(!ok[j]){
			if(st[j])res.push_back(R[i][j]);
			else if(R[i][j])st[j]=1;
		}
	while(res.back())res.pop_back();
	res.pop_back();
	return res;
}

answer.code: In function ‘void send_message(std::vector<bool>, std::vector<bool>)’:
answer.code:20:17: error: ‘send_packet’ was not declared in this scope
   20 |                 send_packet(res);
      |                 ^~~~~~~~~~~