ZJU PAT 1009 Product of Polynomials

def ParseList(list):
dict = {}
for j in range(int(list[0])):
a = int(list[j*2+1])
b = float(list[j*2+2])
dict[a] = b
return dict
dict1 = ParseList(raw_input().split())
dict2 = ParseList(raw_input().split())
dict = {}
for k, v in dict1.iteritems():
for x, y in dict2.iteritems():
a = k + x
b = v * y
if a in dict.keys():
dict[a] = dict[a]+b
if abs(dict[a]) < 0.00001:
del(dict[a])
else:
dict[a] = b
print len(dict),
items = dict.keys()
items.sort()
for item in reversed(items):
print "%d %.1f" % (item, dict[item]),