Python - CVXOPT中的整数线性编程（ILP）函数未生成正确的结果

Question

我试图使用Python 2.7上的CVXOPT库来解决https://en.wikipedia.org/wiki/Integer_programming#Example中的简单示例;最佳答案是（1,2）或（2,2）。我得到了（0.0,0.0）。我在下面的代码中做错了什么？谢谢！

import numpy as np
import cvxopt
from cvxopt import glpk

c=cvxopt.matrix([0,-1]) #-1 since we're maximising the 2nd variable
G=cvxopt.matrix([[-1,1],[3,2],[2,3],[-1,0],[0,-1]],tc='d')
h=cvxopt.matrix([1,12,12,0,0],tc='d')
(status, x)=glpk.ilp(c,G.T,h,B=set([0,1]))
print status
print x[0],x[1]    #should be (1,2) or (2,2)
print sum(c.T*x)