make SCC a struct, and minor 2SAT changes

1 files changed, 22 insertions, 23 deletions

diff --git a/content/graph/scc.cpp b/content/graph/scc.cpp
index 9f8f850..a9e10c1 100644
--- a/content/graph/scc.cpp
+++ b/content/graph/scc.cpp
@@ -1,26 +1,25 @@
-vector<vector<int>> adj;
-vector<int> low, idx, s; // idx enthält Index der SCC pro Knoten
-vector<vector<int>> sccs; // Liste der Knoten pro SCC
+struct SCC {
+	vector<int> idx; // idx enthält Index der SCC pro Knoten
+	vector<vector<int>> sccs; // Liste der Knoten pro SCC
 
-void visit(int v) {
-	int old = low[v] = ssize(s);
-	s.push_back(v);
+	SCC(const vector<vector<int>> &adj): idx(ssize(adj), -1) {
+		vector<int> low(ssize(adj), -1);
+		vector<int> s;
+		auto dfs = [&](auto &&self, int v) -> void {
+			int old = low[v] = ssize(s);
+			s.push_back(v);
 
-	for (auto u : adj[v]) {
-		if (low[u] < 0) visit(u);
-		if (idx[u] < 0) low[v] = min(low[v], low[u]);
-	}
+			for (auto u : adj[v]) {
+				if (low[u] < 0) self(self, u);
+				if (idx[u] < 0) low[v] = min(low[v], low[u]);
+			}
 
-	if (old == low[v]) {
-		sccs.emplace_back(begin(s) + old, end(s));
-		for (int u: sccs.back()) idx[u] = ssize(sccs)-1;
-		s.resize(old);
-}}
-
-void scc() {
-	low.assign(ssize(adj), -1);
-	idx.assign(ssize(adj), -1);
-	sccs.clear();
-	for (int i = 0; i < ssize(adj); i++) {
-		if (low[i] < 0) visit(i);
-}}
+			if (old == low[v]) {
+				sccs.emplace_back(begin(s) + old, end(s));
+				for (int u: sccs.back()) idx[u] = ssize(sccs)-1;
+				s.resize(old);
+		}};
+		for (int i = 0; i < ssize(adj); i++) {
+			if (low[i] < 0) dfs(dfs, i);
+	}}
+};