content/graph/treeIsomorphism.cpp


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vector<vector<int>> adj;
map<vector<int>, int> known; // dont reset!

int treeLabel(int v, int from = -1) {
	vector<int> children;
	for (int u : adj[v]) {
		if (u == from) continue;
		children.push_back(treeLabel(u, v));
	}
	ranges::sort(children);
	if (known.find(children) == known.end()) {
		known[children] = ssize(known);
	}
	return known[children];
}