如下所示：
temp1 = [[] for i in range(10)]
temp2 = [temp1 for i in range(20)]
temp3 = [temp2 for i in range(30)]
for i in range(30):
for j in range(20):
for k in range(10):
temp3[i][j][k] = 0
但是赋值的时候还是发现是指向同一地址的
所以还得这样
matrix3d=[]
for i in range(30):
matrix3d.append([])
for j in range(20):
ma
