/* upsolved after discussion with scott_wu */
#include "message.h"
#include <cstring>
using namespace std;
typedef vector<bool> vb;
typedef vector<vb> vvb;
namespace encoder {
const int N = 1024, K = 66, L = 31;
void encode(vb bb, vb cc) {
int n = bb.size();
bb.resize(N + 1, 0), bb[n] = 1;
vvb aaa(K, vb(L, 0));
for (int u = 0, i = 0; u < L; u++)
if (!cc[u]) {
int d = 1;
while (cc[(u + d) % L])
d++;
aaa[d - 1][u] = 1;
for (int g = d; g < K; g++)
aaa[g][u] = bb[i++];
}
for (int g = 0; g < K; g++)
send_packet(aaa[g]);
}
}
void send_message(vb bb, vb cc) {
encoder::encode(bb, cc);
}
namespace decoder {
const int N = 1024, K = 66, L = 31;
int pp[L]; char visited[L];
vb decode(vvb aaa) {
for (int u = 0; u < L; u++) {
int d = 1;
while (d <= K && aaa[d - 1][u] == 0)
d++;
pp[u] = (u + d) % L;
}
memset(visited, 0, L * sizeof *visited);
int w = -1;
for (int u = 0; u < L; u++) {
int v = u;
while (!visited[v])
visited[v] = -1, v = pp[v];
if (visited[v] == -1) {
int c = 0;
while (visited[v] == -1)
visited[v] = -2, v = pp[v], c++;
if (c == 16) {
w = v;
while (w < pp[w])
w = pp[w];
w = pp[w];
break;
}
}
v = u;
while (visited[v] != 1)
visited[v] = 1, v = pp[v];
}
vb bb(N + 1, 0);
int u = w, i = 0;
do {
int d = 1;
while (d <= K && aaa[d - 1][u] == 0)
d++;
int g = d;
while (g < K)
bb[i++] = aaa[g++][u];
} while ((u = pp[u]) != w);
int n = N;
while (bb[n] == 0)
n--;
bb.resize(n);
return bb;
}
}
vb receive_message(vvb aaa) {
return decoder::decode(aaa);
}
