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// Laufzeit: O(n*min(ans^2, |E|))
vector< vector<int> > adjlist; // Von links nach rechts.
vector<int> pairs; // Der gematchte Knoten oder -1.
vector<bool> visited;
bool dfs(int v) {
if (visited[v]) return false;
visited[v] = true;
for (auto w : adjlist[v]) if (pairs[w] < 0 || dfs(pairs[w])) {
pairs[w] = v; pairs[v] = w; return true;
}
return false;
}
int kuhn(int n) { // n = #Knoten links.
pairs.assign(NUM_VERTICES, -1);
int ans = 0;
// Greedy Matching. Optionale Beschleunigung.
for (int i = 0; i < n; i++) for (auto w : adjlist[i])
if (pairs[w] == -1) { pairs[i] = w; pairs[w] = i; ans++; break; }
for (int i = 0; i < n; i++) if (pairs[i] == -1) {
visited.assign(n, false);
ans += dfs(i);
}
return ans; // Größe des Matchings.
}
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