updated tcr

1 files changed, 84 insertions, 0 deletions

diff --git a/graph/blossom.cpp b/graph/blossom.cpp
new file mode 100644
index 0000000..cc19a2b
--- /dev/null
+++ b/graph/blossom.cpp
@@ -0,0 +1,84 @@
+struct GM {
+	vector<vector<int>> adjlist;
+	// pairs ist der gematchte knoten oder n
+	vector<int> pairs, first, que;
+	vector<pair<int, int>> label;
+	int head, tail;
+
+	GM(int n) : adjlist(n), pairs(n + 1, n), first(n + 1, n), 
+							que(n), label(n + 1, {-1, -1}) {}
+
+	void rematch(int v, int w) {
+		int t = pairs[v]; pairs[v] = w;
+		if (pairs[t] != v) return;
+		if (label[v].second == -1) {
+			pairs[t] = label[v].first;
+			rematch(pairs[t], t);
+		} else {
+			int x = label[v].first;
+			int y = label[v].second;
+			rematch(x, y);
+			rematch(y, x);
+	}}
+
+	int findFirst(int u) {
+		return label[first[u]].first < 0 ? first[u]
+				 : first[u] = findFirst(first[u]);
+	}
+
+	void relabel(int x, int y) {
+		int r = findFirst(x);
+		int s = findFirst(y);
+		if (r == s) return;
+		auto h = label[r] = label[s] = {~x, y};
+		int join;
+		while (true) {
+			if (s != sz(adjlist)) swap(r, s);
+			r = findFirst(label[pairs[r]].first);
+			if (label[r] == h) {
+				join = r;
+				break;
+			} else {
+				label[r] = h;
+		}}
+		for (int v : {first[x], first[y]}) {
+			for (; v != join; v = first[label[pairs[v]].first]) {
+				label[v] = {x, y};
+				first[v] = join;
+				que[tail++] = v;
+	}}}
+
+	bool augment(int u) {
+		label[u] = {sz(adjlist), -1};
+		first[u] = sz(adjlist);
+		head = tail = 0;
+		for (que[tail++] = u; head < tail;) {
+			int x = que[head++];
+			for (int y : adjlist[x]) {
+				if (pairs[y] == sz(adjlist) && y != u) {
+					pairs[y] = x;
+					rematch(x, y);
+					return true;
+				} else if (label[y].first >= 0) {
+					relabel(x, y);
+				} else if (label[pairs[y]].first == -1) {
+					label[pairs[y]].first = x;
+					first[pairs[y]] = y;
+					que[tail++] = pairs[y];
+		}}}
+		return false;
+	}
+
+	int match() {
+		int matching = head = tail = 0;
+		for (int u = 0; u < sz(adjlist); u++) {
+			if (pairs[u] < sz(adjlist) || !augment(u)) continue;
+			matching++;
+			for (int i = 0; i < tail; i++)
+				label[que[i]] = label[pairs[que[i]]] = {-1, -1};
+			label[sz(adjlist)] = {-1, -1};
+		}
+		return matching;
+	}
+
+};
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