File size: 7,481 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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 | #include <bits/stdc++.h>
using namespace std;
struct FastScanner {
static constexpr int BUFSIZE = 1 << 20;
int idx = 0, size = 0;
char buf[BUFSIZE];
inline char readChar() {
if (idx >= size) {
size = (int)fread(buf, 1, BUFSIZE, stdin);
idx = 0;
if (size == 0) return 0;
}
return buf[idx++];
}
template <class T>
bool readInt(T &out) {
char c;
do {
c = readChar();
if (!c) return false;
} while (c <= ' ');
bool neg = false;
if (c == '-') {
neg = true;
c = readChar();
}
T val = 0;
while (c > ' ') {
val = val * 10 + (c - '0');
c = readChar();
}
out = neg ? -val : val;
return true;
}
};
struct FastOutput {
static constexpr int BUFSIZE = 1 << 20;
int idx = 0;
char buf[BUFSIZE];
~FastOutput() { flush(); }
inline void flush() {
if (idx) {
fwrite(buf, 1, idx, stdout);
idx = 0;
}
}
inline void writeChar(char c) {
if (idx >= BUFSIZE) flush();
buf[idx++] = c;
}
inline void writeInt(long long x, char endc = 0) {
if (x == 0) {
writeChar('0');
if (endc) writeChar(endc);
return;
}
if (x < 0) {
writeChar('-');
x = -x;
}
char s[32];
int n = 0;
while (x) {
s[n++] = char('0' + (x % 10));
x /= 10;
}
for (int i = n - 1; i >= 0; --i) writeChar(s[i]);
if (endc) writeChar(endc);
}
};
static inline uint64_t splitmix64(uint64_t &x) {
uint64_t z = (x += 0x9e3779b97f4a7c15ULL);
z = (z ^ (z >> 30)) * 0xbf58476d1ce4e5b9ULL;
z = (z ^ (z >> 27)) * 0x94d049bb133111ebULL;
return z ^ (z >> 31);
}
int main() {
FastScanner fs;
int n, m;
if (!fs.readInt(n)) return 0;
fs.readInt(m);
for (int i = 0; i < 10; i++) {
int tmp;
fs.readInt(tmp);
}
vector<int> U(m), V(m);
vector<int> outdeg(n + 1, 0), indegOrig(n + 1, 0);
for (int i = 0; i < m; i++) {
int u, v;
fs.readInt(u);
fs.readInt(v);
U[i] = u;
V[i] = v;
outdeg[u]++;
indegOrig[v]++;
}
vector<int> outStart(n + 2, 0), inStart(n + 2, 0);
for (int i = 1; i <= n; i++) {
outStart[i + 1] = outStart[i] + outdeg[i];
inStart[i + 1] = inStart[i] + indegOrig[i];
}
vector<int> outTo(m), inTo(m);
vector<int> outPos = outStart, inPos = inStart;
for (int i = 0; i < m; i++) {
int u = U[i], v = V[i];
outTo[outPos[u]++] = v;
inTo[inPos[v]++] = u;
}
vector<int>().swap(U);
vector<int>().swap(V);
// Try DAG longest path via topological sort.
vector<int> indeg = indegOrig;
vector<int> q;
q.reserve(n);
for (int i = 1; i <= n; i++) if (indeg[i] == 0) q.push_back(i);
vector<int> topo;
topo.reserve(n);
for (size_t qi = 0; qi < q.size(); qi++) {
int u = q[qi];
topo.push_back(u);
for (int e = outStart[u]; e < outStart[u + 1]; e++) {
int v = outTo[e];
if (--indeg[v] == 0) q.push_back(v);
}
}
vector<int> bestPath;
if ((int)topo.size() == n) {
vector<int> dp(n + 1, 1), par(n + 1, -1);
int bestEnd = 1, bestLen = 1;
for (int u : topo) {
int du = dp[u];
for (int e = outStart[u]; e < outStart[u + 1]; e++) {
int v = outTo[e];
if (du + 1 > dp[v]) {
dp[v] = du + 1;
par[v] = u;
}
}
if (dp[u] > bestLen) {
bestLen = dp[u];
bestEnd = u;
}
}
for (int i = 1; i <= n; i++) {
if (dp[i] > bestLen) {
bestLen = dp[i];
bestEnd = i;
}
}
vector<int> path;
path.reserve(bestLen);
int cur = bestEnd;
while (cur != -1) {
path.push_back(cur);
cur = par[cur];
}
reverse(path.begin(), path.end());
bestPath = std::move(path);
} else {
// Fallback heuristic: bidirectional greedy from several starts.
int maxOutV = 1;
for (int i = 2; i <= n; i++) if (outdeg[i] > outdeg[maxOutV]) maxOutV = i;
int anyIndeg0 = -1;
for (int i = 1; i <= n; i++) if (indegOrig[i] == 0) { anyIndeg0 = i; break; }
vector<int> starts;
starts.reserve(16);
starts.push_back(1);
starts.push_back(maxOutV);
if (anyIndeg0 != -1) starts.push_back(anyIndeg0);
uint64_t seed = 123456789123456789ULL ^ (uint64_t)n ^ ((uint64_t)m << 1);
int targetAttempts = 10;
while ((int)starts.size() < targetAttempts) {
int v = (int)(splitmix64(seed) % (uint64_t)n) + 1;
starts.push_back(v);
}
sort(starts.begin(), starts.end());
starts.erase(unique(starts.begin(), starts.end()), starts.end());
vector<int> vis(n + 1, 0);
int stamp = 0;
auto getBestOut = [&](int u, int st) -> int {
int best = -1;
int bestScore = -1;
for (int e = outStart[u]; e < outStart[u + 1]; e++) {
int v = outTo[e];
if (vis[v] == st) continue;
int score = outdeg[v];
if (score > bestScore) {
bestScore = score;
best = v;
}
}
return best;
};
auto getBestIn = [&](int u, int st) -> int {
int best = -1;
int bestScore = -1;
for (int e = inStart[u]; e < inStart[u + 1]; e++) {
int v = inTo[e]; // v -> u
if (vis[v] == st) continue;
int score = outdeg[v];
if (score > bestScore) {
bestScore = score;
best = v;
}
}
return best;
};
size_t attempts = min<size_t>(starts.size(), 12);
for (size_t ai = 0; ai < attempts; ai++) {
int s = starts[ai];
stamp++;
deque<int> dq;
dq.push_back(s);
vis[s] = stamp;
while (true) {
int back = dq.back();
int nxt = getBestOut(back, stamp);
if (nxt != -1) {
dq.push_back(nxt);
vis[nxt] = stamp;
continue;
}
int front = dq.front();
int pre = getBestIn(front, stamp);
if (pre != -1) {
dq.push_front(pre);
vis[pre] = stamp;
continue;
}
break;
}
if (dq.size() > bestPath.size()) {
bestPath.assign(dq.begin(), dq.end());
if (bestPath.size() == (size_t)n) break;
}
}
if (bestPath.empty()) bestPath = {1};
}
FastOutput fo;
fo.writeInt((int)bestPath.size(), '\n');
for (size_t i = 0; i < bestPath.size(); i++) {
fo.writeInt(bestPath[i], (i + 1 == bestPath.size()) ? '\n' : ' ');
}
return 0;
} |