贪婪算法

Posted 2021-01-18 j657521265

要求是用最少的电台覆盖最多的州，每个电台所能覆盖的州不一样

算法思路：每次将所有集合和总集合求交集，留下交集len最长的哪个，再用总集合-留下集合进行下一轮循环，直到总集合为0

states = 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:
    best_stationname = None
    states_covered = set()
    #这里这个for，第一个是遍历的name，第二个遍历的是set
    for stationname, stationset in stations.items():
        covered = states & stationset
        if len(covered) > len(states_covered):
            best_stationname = stationname
            states_covered = covered
    states = states - states_covered
    final_stations.add(best_stationname)

print final_stations