#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#pragma GCC optimize("O3")
#define all(a) (a).begin(), (a).end()
#define ull unsigned long long
#define ll long long
typedef tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update> ordered_set_ll;
typedef tree<pair<ll, ll>, null_type, less<pair<ll, ll>>, rb_tree_tag, tree_order_statistics_node_update> ordered_set_p;
ll ceil_div(ll a, ll b) {
if (a % b == 0) return a / b;
else return a / b + 1;
}
struct splitmix_hash {
public:
size_t operator()(ull x) const {
static const ull FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
x += FIXED_RANDOM;
x += 0x9e3779b97f4a7c15;
x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
return x ^ (x >> 31);
}
};
struct pairhash {
public:
template <typename T, typename U>
std::size_t operator()(const std::pair<T, U> &x) const {
int n = std::hash<T>()(x.first) ^ std::hash<U>()(x.second);
return splitmix_hash()(n);
}
};
#define MOD 1000000007
ll bin_pow(ll a, ll p) {
vector<ll> powers(31);
powers[1] = a;
for (int i = 2; i < 31; i++) {
powers[i] = (powers[i - 1] * powers[i - 1]) % MOD;
}
int s = 0;
ll res = 1;
while (p >> s) {
if ((p >> s) & 1) res = (res * powers[s + 1]) % MOD;
s++;
}
return res;
}
// vector<ll> fact(1e6 + 1), rev_fact(1e6 + 1);
// ll choose(ll k, ll n) {
// if (k > n) return 0;
// return ((fact[n] * rev_fact[k]) % MOD * rev_fact[n - k]) % MOD;
// }
#include "transfer.h"
vector<int> get_attachment(vector<int> source) {
int l = 0;
while (source.size() >> l) l++;
vector<int> res(l + 1);
for (int i = 1; i <= source.size(); i++) {
for (int s = 0; s < l; s++) {
if ((i >> s) & 1) res[s] ^= source[i];
}
res[l] ^= source[i];
}
return res;
}
vector<int> retrieve(vector<int> data) {
int l;
if (data.size() == 70) l = 6;
else l = 8;
vector<int> res(l + 1), expected(data.end() - l - 1, data.end());
data.resize(data.size() - l - 1);
for (int i = 1; i < data.size(); i++) {
for (int s = 0; s < l; s++) {
if ((i >> s) & 1) res[s] ^= source[i];
}
res[l] ^= source[i];
}
if (res[l] == expected[l]) return data;
int swapped = 0;
for (int s = 0; s < l; s++) {
if (res[s] != expected[s]) swapped |= 1 << s;
}
if (swapped == 0) return data;
data[swapped - 1] ^= 1;
return data;
}
Compilation message
transfer.cpp: In function 'std::vector<int> get_attachment(std::vector<int>)':
transfer.cpp:71:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
71 | for (int i = 1; i <= source.size(); i++) {
| ~~^~~~~~~~~~~~~~~~
transfer.cpp: In function 'std::vector<int> retrieve(std::vector<int>)':
transfer.cpp:87:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
87 | for (int i = 1; i < data.size(); i++) {
| ~~^~~~~~~~~~~~~
transfer.cpp:89:41: error: 'source' was not declared in this scope
89 | if ((i >> s) & 1) res[s] ^= source[i];
| ^~~~~~
transfer.cpp:91:19: error: 'source' was not declared in this scope
91 | res[l] ^= source[i];
| ^~~~~~
