所以,我从
我正在尝试理解集合和设置封面,所以我对此进行了一些修改。
U = set([1,2,3,4])
R = U
S = [set([1,2]),
set([1]),
set([1,2,3]),
set([1]),
set([3]),
set([1,2]),
set([3]),
set([1,2,3])]
w = [1, 1, 1, 1, 1, 1, 1, 1]
C = []
costs = []
def findMin(S, R):
minCost = 99999.0
minElement = -1
for i, s in enumerate(S):
try:
cost = w[i]/(len(s.intersection(R)))
if cost < minCost:
minCost = cost
minElement = i
except:
# Division by zero, ignore
pass
return S[minElement], w[minElement]
while len(R) != 0:
S_i, cost = findMin(S, R)
C.append(S_i)
R = R.difference(S_i)
costs.append(cost)
print "Cover: ", C
#print "Total Cost: ", sum(costs), costs
可以看出,U 的值为 1,2,3,4。没有一组中有 4 个。我不懂权重,所以把它们设为 1。
预期输出:set([1,2])
、set([3])
、set([1,2,3])
或 覆盖可用最大值的内容。