#include "transfer.h"
#include <bits/stdc++.h>
using namespace std;
std::vector<int> get_attachment(std::vector<int> source) {
int N = (int)source.size();
vector<int> send = source;
int b = 0;
while((1 << b) <= (N+1)) ++b;
vector<int> parity(b);
// cout << b << '\n';
for(int i = 0; i < N; ++i) if(source[i] == 0){
for(int j = 0; j < b; ++j) if((i+1) >> j & 1) parity[j] ^= 1;
}
// for(auto it : send) cout << it; cout << '\n';
return parity;
}
std::vector<int> retrieve(std::vector<int> data) {
int L = (int)data.size();
//L = N + 32 - __builtin_clz(N)
// for(auto it : data) cout << it; cout << '\n';
int N = -1, b = -1;
for(int i = 1; i < L; ++i){
int nbit = 0;
while((1 << nbit) <= i+1) ++nbit;
// cout << i << ' ' << nbit << '\n';
if(i + nbit == L){
N = i;
b = nbit;
break;
}
}
assert(N != -1);
vector<int> cur(b), fix(data.begin() + N, data.end());
vector<int> receive(data.begin(), data.begin() + N);
for(int i = 0; i < N; ++i) if(data[i] == 0){
for(int j = 0; j < b; ++j) if((i+1) >> j & 1) cur[j] ^= 1;
}
assert((int)cur.size() == (int)fix.size());
int changed = 0;
for(int i = 0; i < b; ++i){
if(cur[i] != fix[i]) changed |= (1 << i);
}
if(changed != 0){
receive[changed-1] ^= 1;
}
return receive;
}
