File size: 5,207 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 | #include <bits/stdc++.h>
using namespace std;
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
int n, m;
cin >> n >> m;
vector<int> a(10);
for (int i = 0; i < 10; ++i) cin >> a[i]; // unused
vector<vector<int>> adj(n + 1), radj(n + 1);
for (int i = 0; i < m; ++i) {
int u, v;
cin >> u >> v;
adj[u].push_back(v);
radj[v].push_back(u);
}
// sort adjacency lists for binary search
for (int i = 1; i <= n; ++i) {
sort(adj[i].begin(), adj[i].end());
}
vector<int> outdegree(n + 1), indegree(n + 1);
for (int i = 1; i <= n; ++i) {
outdegree[i] = adj[i].size();
indegree[i] = radj[i].size();
}
// choose start vertex: first look for a vertex with indegree 0
int start = -1;
for (int i = 1; i <= n; ++i) {
if (indegree[i] == 0) {
if (start == -1 || outdegree[i] > outdegree[start]) {
start = i;
}
}
}
if (start == -1) {
// no vertex with indegree 0, pick by (outdegree - indegree)
int best_score = outdegree[1] - indegree[1];
start = 1;
for (int i = 2; i <= n; ++i) {
int score = outdegree[i] - indegree[i];
if (score > best_score || (score == best_score && outdegree[i] > outdegree[start])) {
best_score = score;
start = i;
}
}
}
vector<bool> visited(n + 1, false);
vector<int> path;
// greedy walk from start
int cur = start;
while (true) {
visited[cur] = true;
path.push_back(cur);
int nxt = -1;
int best_out = -1;
for (int v : adj[cur]) {
if (!visited[v] && outdegree[v] > best_out) {
best_out = outdegree[v];
nxt = v;
}
}
if (nxt == -1) break;
cur = nxt;
}
// extend front using reverse edges
while (true) {
int first = path[0];
bool found = false;
for (int v : radj[first]) {
if (!visited[v]) {
path.insert(path.begin(), v);
visited[v] = true;
found = true;
break;
}
}
if (!found) break;
}
// extend back using forward edges
while (true) {
int last = path.back();
bool found = false;
for (int v : adj[last]) {
if (!visited[v]) {
path.push_back(v);
visited[v] = true;
found = true;
break;
}
}
if (!found) break;
}
// convert to linked list representation
vector<int> next(n + 1, -1), prev(n + 1, -1);
int head = path[0];
int tail = path.back();
for (size_t i = 0; i + 1 < path.size(); ++i) {
next[path[i]] = path[i + 1];
prev[path[i + 1]] = path[i];
}
// collect unvisited vertices
vector<int> unvisited;
for (int v = 1; v <= n; ++v) {
if (!visited[v]) unvisited.push_back(v);
}
// insertion passes
const int MAX_PASSES = 10;
for (int pass = 0; pass < MAX_PASSES; ++pass) {
bool changed = false;
for (auto it = unvisited.begin(); it != unvisited.end(); ) {
int v = *it;
bool inserted = false;
// try to insert before head
if (!inserted && binary_search(adj[v].begin(), adj[v].end(), head)) {
prev[head] = v;
next[v] = head;
head = v;
visited[v] = true;
inserted = true;
}
// try to insert after tail
if (!inserted && binary_search(adj[tail].begin(), adj[tail].end(), v)) {
next[tail] = v;
prev[v] = tail;
tail = v;
visited[v] = true;
inserted = true;
}
// try to insert between two consecutive vertices
if (!inserted) {
for (int u : radj[v]) {
if (visited[u]) {
int w = next[u];
if (w != -1 && binary_search(adj[v].begin(), adj[v].end(), w)) {
next[u] = v;
prev[v] = u;
next[v] = w;
prev[w] = v;
visited[v] = true;
inserted = true;
break;
}
}
}
}
if (inserted) {
it = unvisited.erase(it);
changed = true;
} else {
++it;
}
}
if (!changed) break;
}
// reconstruct final path from head
vector<int> final_path;
cur = head;
while (cur != -1) {
final_path.push_back(cur);
cur = next[cur];
}
// output
cout << final_path.size() << "\n";
for (size_t i = 0; i < final_path.size(); ++i) {
if (i > 0) cout << " ";
cout << final_path[i];
}
cout << endl;
return 0;
} |