a = range(1,10)

#1 variant
for i in a:
    rev = (-1,1)[i % 2]
    print " ".join(map(str, a[:i][::rev]))

#2 variant
d = [[str(j) for j in a[:i][::(-1,1)[i % 2]]] for i in a]
print "\n".join([" ".join(j) for j in d])