#include "transfer.h"
#include <bits/stdc++.h>
using namespace std;
std::vector<int> get_attachment(std::vector<int> source) {
int n = source.size();
int xr = 0;
for (int i = 0; i < n; i++) {
xr ^= source[i] * (i + 1);
}
int k = n == 63 ? 6 : 8;
vector<int> attachment(k + 1);
for (int i = 0; i < k; i++) {
attachment[i] = xr >> i & 1;
}
attachment[k] = __builtin_popcount(xr) & 1;
return attachment;
}
std::vector<int> retrieve(std::vector<int> data) {
int n = data.size();
int k = n == 63 + 7 ? 6 : 8;
n -= k + 1;
int parity = 0;
for (int i = n; i < n + k + 1; i++) {
parity = (parity + data[i]) & 1;
}
if (!(parity & 1)) {
int xr = 0;
for (int i = n; i < n + k; i++) {
xr += data[i] << (i - n);
}
for (int i = 0; i < n; i++) {
xr ^= data[i] * (i + 1);
}
if (xr > 0) {
data[xr - 1] ^= 1;
}
}
return vector<int>(data.begin(), data.end() - k - 1);
}
