File size: 5,771 Bytes
1fd0050 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 | #include <bits/stdc++.h>
using namespace std;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, m;
if (!(cin >> n >> m)) return 0;
// Read scoring parameters (unused)
for (int i = 0; i < 10; ++i) {
int tmp; cin >> tmp;
}
vector<int> U(m), V(m);
vector<int> outdeg(n + 1, 0), indeg(n + 1, 0);
for (int i = 0; i < m; ++i) {
int u, v; cin >> u >> v;
U[i] = u; V[i] = v;
++outdeg[u];
++indeg[v];
}
// Build CSR for outgoing edges
vector<int> outStart(n + 2, 0), inStart(n + 2, 0);
for (int i = 1; i <= n; ++i) outStart[i + 1] = outStart[i] + outdeg[i];
for (int i = 1; i <= n; ++i) inStart[i + 1] = inStart[i] + indeg[i];
vector<int> outAdj(m), inAdj(m);
vector<int> curOut = outStart, curIn = inStart;
for (int i = 0; i < m; ++i) {
int u = U[i], v = V[i];
outAdj[curOut[u]++] = v;
inAdj[curIn[v]++] = u;
}
// Candidate starts
vector<int> nodes(n);
iota(nodes.begin(), nodes.end(), 1);
auto cmp_out_minus_in = [&](int a, int b){
int da = outdeg[a] - indeg[a];
int db = outdeg[b] - indeg[b];
if (da != db) return da > db;
return outdeg[a] > outdeg[b];
};
auto cmp_in_minus_out = [&](int a, int b){
int da = indeg[a] - outdeg[a];
int db = indeg[b] - outdeg[b];
if (da != db) return da > db;
return indeg[a] > indeg[b];
};
auto cmp_out = [&](int a, int b){
if (outdeg[a] != outdeg[b]) return outdeg[a] > outdeg[b];
return indeg[a] > indeg[b];
};
auto cmp_in = [&](int a, int b){
if (indeg[a] != indeg[b]) return indeg[a] > indeg[b];
return outdeg[a] > outdeg[b];
};
vector<int> cand;
cand.reserve(250);
{
vector<int> tmp = nodes;
sort(tmp.begin(), tmp.end(), cmp_out_minus_in);
int K = min<int>(50, tmp.size());
for (int i = 0; i < K; ++i) cand.push_back(tmp[i]);
}
{
vector<int> tmp = nodes;
sort(tmp.begin(), tmp.end(), cmp_in_minus_out);
int K = min<int>(50, tmp.size());
for (int i = 0; i < K; ++i) cand.push_back(tmp[i]);
}
{
vector<int> tmp = nodes;
sort(tmp.begin(), tmp.end(), cmp_out);
int K = min<int>(50, tmp.size());
for (int i = 0; i < K; ++i) cand.push_back(tmp[i]);
}
{
vector<int> tmp = nodes;
sort(tmp.begin(), tmp.end(), cmp_in);
int K = min<int>(50, tmp.size());
for (int i = 0; i < K; ++i) cand.push_back(tmp[i]);
}
// Add random candidates
uint64_t seed = chrono::high_resolution_clock::now().time_since_epoch().count();
auto rng = [&]()->uint64_t {
seed ^= seed << 7;
seed ^= seed >> 9;
return seed;
};
for (int i = 0; i < 50 && i < n; ++i) {
int v = (rng() % n) + 1;
cand.push_back(v);
}
// Deduplicate candidates and cap total
sort(cand.begin(), cand.end());
cand.erase(unique(cand.begin(), cand.end()), cand.end());
if ((int)cand.size() > 200) cand.resize(200);
vector<int> bestPath;
bestPath.reserve(n);
int bestLen = 0;
vector<int> vis(n + 1, 0);
int curMark = 1;
auto build_from_start = [&](int s) {
++curMark;
if (curMark == 0) { // overflow safety
fill(vis.begin(), vis.end(), 0);
curMark = 1;
}
vis[s] = curMark;
vector<int> path; path.reserve(n);
path.push_back(s);
auto score = [&](int v)->int {
// Heuristic score
return outdeg[v]*2 + indeg[v];
};
// Extend back
while (true) {
int u = path.back();
int bestv = -1;
int bests = -1;
int l = outStart[u], r = outStart[u+1];
for (int i = l; i < r; ++i) {
int v = outAdj[i];
if (vis[v] == curMark) continue;
int sc = score(v);
if (sc > bests || (sc == bests && (rng() & 1))) {
bests = sc;
bestv = v;
}
}
if (bestv == -1) break;
vis[bestv] = curMark;
path.push_back(bestv);
}
// Extend front
vector<int> prefix; prefix.reserve(n);
while (true) {
int u = path.front();
int bestv = -1;
int bests = -1;
int l = inStart[u], r = inStart[u+1];
for (int i = l; i < r; ++i) {
int v = inAdj[i];
if (vis[v] == curMark) continue;
int sc = score(v);
if (sc > bests || (sc == bests && (rng() & 1))) {
bests = sc;
bestv = v;
}
}
if (bestv == -1) break;
vis[bestv] = curMark;
prefix.push_back(bestv);
}
int len = (int)path.size() + (int)prefix.size();
if (len > bestLen) {
bestLen = len;
bestPath.clear();
bestPath.reserve(len);
for (int i = (int)prefix.size() - 1; i >= 0; --i) bestPath.push_back(prefix[i]);
for (int x : path) bestPath.push_back(x);
}
};
if (cand.empty()) cand.push_back(1);
for (int s : cand) {
build_from_start(s);
if (bestLen == n) break;
}
if (bestLen == 0) {
// Fallback: at least a single vertex
bestLen = 1;
bestPath.clear();
bestPath.push_back(1);
}
cout << bestLen << "\n";
for (int i = 0; i < bestLen; ++i) {
if (i) cout << ' ';
cout << bestPath[i];
}
cout << "\n";
return 0;
} |