// Source: https://usaco.guide/general/io

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

// vector<vector<bool>> hehe;

// vector<bool> send_packet(vector<bool> e){
// 	hehe.push_back(e);
// 	return e;
// }

void send_message(vector<bool> m, vector<bool> c){
	assert(c.size() == 31);
	int nxt[31];
	int diff = 0;
	for(int i = 0;i < 31;i++){
		nxt[i] = 66;
		if(c[i]){
			continue;
		}
		for(int j = 1;j < 31;j++){
			if(!c[(i+j)%31]){
				nxt[i] = j;
				diff += j;
				break;
			}
		}
	}
	bool tmp = !m.back();
	while(m.size() < 1025){
		m.push_back(tmp);
	}
	vector<bool> ret[66];
	for(int i = 0;i < 66;i++){
		ret[i].resize(31);
	}
	int pos = 0;
	for(int i = 0;i < 31;i++){
		for(int j = 0;j < nxt[i]-1;j++){
			ret[j][i] = 0;
		}
		ret[nxt[i]-1][i] = 1;
		for(int j = nxt[i];j < 66;j++){
			ret[j][i] = m[pos++];
		}
	}
	for(int i = 0;i < 66;i++){
		send_packet(ret[i]);
	}
}

vector<bool> receive_message(vector<vector<bool>> r){
	int nxt[31];
	for(int i = 0;i < 31;i++){
		nxt[i] = 66;
		for(int j = 0;j < 66;j++){
			if(r[j][i]){
				nxt[i] = (i+j+1)%31;
				break;
			}
		}
	}
	int good = -1;
	for(int i = 0;i < 31;i++){
		int u = i;
		for(int j = 0;j < 16;j++){
			u = nxt[u];
		}
		if(u == i){
			good = i;
			break;
		}
	}
	vector<bool> ret;
	for(int i = 0;i < 16;i++){
		int j = 0;
		while(j < 66 and !r[j][good]){
			j++;
		}
		j++;
		while(j < 66){
			ret.push_back(r[j][good]);
			j++;
		}
		good = nxt[good];
	}
	char c = ret.back();
	while(ret.back() == c){
		ret.pop_back(0);
	}
	assert(ret.size());
	//ret.pop_back();
	return ret;
}

// int main() {
// 	int n;
// 	cin >> n;
// 	vector<bool> a;
// 	vector<bool> c(31,0);
// 	for(int i = 0;i < n;i++){
// 		char c;
// 		cin >> c;
// 		a.push_back(c-'0');
// 	}
// 	for(int i = 1;i < 31;i += 2){
// 		c[i] = 1;
// 	}
// 	send_message(a,c);
// 	vector<bool> ans = receive_message(hehe);
// 	assert(ans == a);
// 	for(auto i : ans){
// 		cout << i;
// 	}
// }

answer.code: In function ‘std::vector<bool> receive_message(std::vector<std::vector<bool> >)’:
answer.code:91:29: error: no matching function for call to ‘std::vector<bool>::pop_back(int)’
   91 |                 ret.pop_back(0);
      |                 ~~~~~~~~~~~~^~~
In file included from /usr/include/c++/11/vector:68,
                 from /usr/include/c++/11/functional:62,
                 from /usr/include/c++/11/pstl/glue_algorithm_defs.h:13,
                 from /usr/include/c++/11/algorithm:74,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:65,
                 from answer.code:3:
/usr/include/c++/11/bits/stl_bvector.h:1058:7: note: candidate: ‘void std::vector<bool, _Alloc>::pop_back() [with _Alloc = std::allocator<bool>]’
 1058 |       pop_back()
      |       ^~~~~~~~
/usr/include/c++/11/bits/stl_bvector.h:1058:7: note:   candidate expects 0 arguments, 1 provided