Merge pull request #11 from SebVde/new-heuristic

Implemented the constructive greedy heuristic

Author: SebVde

constr_heur.py

@@ -0,0 +1,21 @@
+import networkx as nx
+
+
+def find_min_fvs(G):
+    fvs = set()
+    while True:
+        try:
+            cycle = nx.find_cycle(G)
+        except nx.NetworkXNoCycle:
+            break
+
+        cycle_nodes = {node for e in cycle for node in e}
+        v = max(cycle_nodes, key=lambda x: G.degree(x))
+        fvs.add(v)
+        G.remove_node(v)
+
+    return fvs
+
+
+def get_decycling_number_constr_heur(G):
+    return len(find_min_fvs(G.copy()))