Greedy algorithm implemented in Python

# Use Python to achieve greedy algorithm 
# set covering problem 
# Suppose you do a radio show, to make the nation's 50 states listeners are listening to. To do this, you need to decide which aired on broadcast stations. Broadcast in each broadcast station would need to pay for it, so you tried to radio station in as little broadcast # 1. Create a list that contains to be covered by the state states_needed = the SET ([ "MT", "WA", "or", "the above mentioned id", "nv", "UT", "CA", "az"]) # 2. use hash table represent alternative radio station list stations = dict () stations [ "KONE"] = SET ([ "ID", "NV", "UT"]) Stations [ "ktwo"] = SET ([ "WA", " 



"NV", "CA"]) Stations [ "kfour"] = SET ([ "NV", "UT"]) Stations [ "kfive"] = SET ([ "CA", "AZ"]) 
#. 3. used to store the final set of selected broadcast station 
final_stations = sET () 
# 5. the cycle 
 the while states_needed: 
 # through all broadcast stations, covering most select uncovered state broadcasting station, the broadcast station is stored in the best_station the 
 best_station = none 
  # all states not covered by this set contains the broadcast station coverage 
 states_covered = the SET () 
 for station, States in stations. items (): 
covered's = states_needed States & 
 IF len (covered's)>len(states_covered):
 best_station = station
 states_covered = covered
 states_needed -= states_covered
 final_stations.add(best_station)

print(final_stations) # 结果为{'ktwo', 'kthree', 'kone', 'kfive'}