1 files changed, 23 insertions, 0 deletions
diff --git a/content/graph/euler.cpp b/content/graph/euler.cpp
new file mode 100644
index 0000000..a5ea192
--- /dev/null
+++ b/content/graph/euler.cpp
@@ -0,0 +1,23 @@
+vector<vector<int>> idx;
+vector<int> to, validIdx, cycle;
+vector<bool> used;
+
+void addEdge(int u, int v) {
+	idx[u].push_back(sz(to));
+	to.push_back(v);
+	used.push_back(false);
+	idx[v].push_back(sz(to)); // für ungerichtet
+	to.push_back(u);
+	used.push_back(false);
+}
+
+void euler(int v) { // init idx und validIdx
+	for (;validIdx[v] < sz(idx[v]); validIdx[v]++) {
+		if (!used[idx[v][validIdx[v]]]) {
+			int u = to[idx[v][validIdx[v]]];
+			used[idx[v][validIdx[v]]] = true;
+			used[idx[v][validIdx[v]] ^ 1] = true; // für ungerichtet
+			euler(u);
+	}}
+	cycle.push_back(v); // Zyklus in umgekehrter Reihenfolge.
+}