code for chapter 8

08_greedy_algorithms/python/01_set_covering.py

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+# You pass an array in, and it gets converted to a set.
+states_needed = set(["mt", "wa", "or", "id", "nv", "ut", "ca", "az"])
+
+stations = {}
+stations["kone"] = set(["id", "nv", "ut"])
+stations["ktwo"] = set(["wa", "id", "mt"])
+stations["kthree"] = set(["or", "nv", "ca"])
+stations["kfour"] = set(["nv", "ut"])
+stations["kfive"] = set(["ca", "az"])
+
+final_stations = set()
+
+while states_needed:
+  best_station = None
+  states_covered = set()
+  for station, states in stations.items():
+    covered = states_needed & states
+    if len(covered) > len(states_covered):
+      best_station = station
+      states_covered = covered
+
+  states_needed -= states_covered
+  final_stations.add(best_station)
+
+print final_stations