From 5ab8a5088b729a9953b8dff1b2a985dc8fb2098b Mon Sep 17 00:00:00 2001
From: mzuenni <michi.zuendorf@gmail.com>
Date: Mon, 27 Jun 2022 17:19:28 +0200
Subject: updated tcr

---
 graph/havelHakimi.cpp | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 graph/havelHakimi.cpp

(limited to 'graph/havelHakimi.cpp')

diff --git a/graph/havelHakimi.cpp b/graph/havelHakimi.cpp
new file mode 100644
index 0000000..9fb9846
--- /dev/null
+++ b/graph/havelHakimi.cpp
@@ -0,0 +1,19 @@
+vector<vector<int>> havelHakimi(const vector<int>& deg) {
+	priority_queue<pair<int, int>> pq;
+	for (int i = 0; i < sz(deg); i++) pq.push({deg[i], i});
+	vector<vector<int>> adj;
+	while (!pq.empty()) {
+		auto v = pq.top(); pq.pop();
+		if (sz(pq) < v.first) return {}; //ERROR
+		vector<pair<int, int>> todo;
+		for (int i = 0; i < v.first; i++) {
+			auto u = pq.top(); pq.pop();
+			adj[v.second].push_back(u.second);
+			adj[u.second].push_back(v.second);
+			u.first--;
+			if (u.first > 0) todo.push_back(u);
+		}
+		for (auto e : todo) pq.push(e);
+	}
+	return adj;
+} 
-- 
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