File size: 6,948 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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 | #include <bits/stdc++.h>
using namespace std;
// Fast input
struct FastScanner {
static const int BUFSIZE = 1 << 20;
int idx = 0, size = 0;
char buf[BUFSIZE];
inline char getChar() {
if (idx >= size) {
size = (int)fread(buf, 1, BUFSIZE, stdin);
idx = 0;
if (size == 0) return 0;
}
return buf[idx++];
}
template <typename T>
bool nextInt(T &out) {
char c; T sign = 1; T val = 0;
c = getChar();
if (!c) return false;
while (c != '-' && (c < '0' || c > '9')) {
c = getChar();
if (!c) return false;
}
if (c == '-') { sign = -1; c = getChar(); }
for (; c >= '0' && c <= '9'; c = getChar()) val = val * 10 + (c - '0');
out = val * sign;
return true;
}
} In;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, m;
if (!In.nextInt(n)) return 0;
In.nextInt(m);
// Read scoring parameters (unused)
for (int i = 0; i < 10; ++i) {
int tmp; In.nextInt(tmp);
}
vector<vector<int>> outScan(n + 1), inScan(n + 1);
outScan.shrink_to_fit();
inScan.shrink_to_fit();
// Read edges
for (int i = 0; i < m; ++i) {
int u, v; In.nextInt(u); In.nextInt(v);
if (u >= 1 && u <= n && v >= 1 && v <= n && u != v) {
outScan[u].push_back(v);
inScan[v].push_back(u);
}
}
// Build sorted out adjacency for membership tests
vector<vector<int>> outSorted(n + 1);
for (int u = 1; u <= n; ++u) {
outSorted[u] = outScan[u];
sort(outSorted[u].begin(), outSorted[u].end());
outSorted[u].erase(unique(outSorted[u].begin(), outSorted[u].end()), outSorted[u].end());
}
auto hasEdge = [&](int u, int v) -> bool {
const auto &vec = outSorted[u];
auto it = lower_bound(vec.begin(), vec.end(), v);
return (it != vec.end() && *it == v);
};
vector<int> degOut(n + 1), degIn(n + 1);
for (int u = 1; u <= n; ++u) {
degOut[u] = (int)outScan[u].size();
degIn[u] = (int)inScan[u].size();
}
// Attempt runner
auto runAttempt = [&](int start, int maxInsertionPasses) -> vector<int> {
vector<char> used(n + 1, 0);
vector<int> nxt(n + 1, 0), prv(n + 1, 0);
vector<int> outIter(n + 1, 0), inIter(n + 1, 0);
int head = start, tail = start;
used[start] = 1;
auto extendEnds = [&]() {
while (true) {
bool progressed = false;
// Extend right (tail)
while (true) {
auto &vec = outScan[tail];
int &pos = outIter[tail];
while (pos < (int)vec.size() && used[vec[pos]]) pos++;
if (pos >= (int)vec.size()) break;
int v = vec[pos++];
if (used[v]) continue;
nxt[tail] = v;
prv[v] = tail;
nxt[v] = 0;
used[v] = 1;
tail = v;
progressed = true;
}
// Extend left (head)
while (true) {
auto &vec = inScan[head];
int &pos = inIter[head];
while (pos < (int)vec.size() && used[vec[pos]]) pos++;
if (pos >= (int)vec.size()) break;
int u = vec[pos++];
if (used[u]) continue;
prv[head] = u;
nxt[u] = head;
prv[u] = 0;
used[u] = 1;
head = u;
progressed = true;
}
if (!progressed) break;
}
};
extendEnds();
auto insertionPass = [&]() -> bool {
bool changed = false;
int u = head;
while (u != 0) {
int w = nxt[u];
if (w == 0) break;
auto &neighbors = outScan[u];
for (int id = 0; id < (int)neighbors.size(); ++id) {
int v = neighbors[id];
if (!used[v] && hasEdge(v, w)) {
// insert v between u and w
nxt[u] = v;
prv[v] = u;
nxt[v] = w;
prv[w] = v;
used[v] = 1;
w = v; // new w for further chaining
changed = true;
}
}
u = w; // continue from the last inserted node towards tail
}
return changed;
};
for (int pass = 0; pass < maxInsertionPasses; ++pass) {
bool ch = insertionPass();
if (!ch) break;
extendEnds();
}
// Build result sequence
vector<int> ans;
ans.reserve(n);
for (int u = head; u != 0; u = nxt[u]) ans.push_back(u);
return ans;
};
// Prepare start candidates
int startMaxDegSum = 1, startMaxOut = 1, startMaxIn = 1;
for (int u = 2; u <= n; ++u) {
if (degOut[u] + degIn[u] > degOut[startMaxDegSum] + degIn[startMaxDegSum]) startMaxDegSum = u;
if (degOut[u] > degOut[startMaxOut]) startMaxOut = u;
if (degIn[u] > degIn[startMaxIn]) startMaxIn = u;
}
vector<int> starts;
auto push_unique = [&](int v) {
if (v < 1 || v > n) return;
for (int x : starts) if (x == v) return;
starts.push_back(v);
};
push_unique(startMaxDegSum);
push_unique(startMaxOut);
push_unique(startMaxIn);
// Random candidates
std::mt19937_64 rng((uint64_t)chrono::high_resolution_clock::now().time_since_epoch().count());
int randomTrials = 5;
for (int i = 0; i < randomTrials; ++i) {
int v = (int)(rng() % n) + 1;
push_unique(v);
}
vector<int> bestPath;
size_t bestLen = 0;
// Time budget (rough)
auto t0 = chrono::high_resolution_clock::now();
const double timeBudget = 3.8; // seconds
for (size_t i = 0; i < starts.size(); ++i) {
auto t1 = chrono::high_resolution_clock::now();
double elapsed = chrono::duration<double>(t1 - t0).count();
if (elapsed > timeBudget) break;
int start = starts[i];
vector<int> cand = runAttempt(start, 2);
if (cand.size() > bestLen) {
bestLen = cand.size();
bestPath.swap(cand);
if (bestLen == (size_t)n) break;
}
}
if (bestPath.empty()) {
// Fallback: output at least one vertex
bestPath.push_back(1);
}
cout << bestPath.size() << "\n";
for (size_t i = 0; i < bestPath.size(); ++i) {
if (i) cout << ' ';
cout << bestPath[i];
}
cout << "\n";
return 0;
} |