rang 练习题

sum = 0
for i in range(1, 100):
    if i % 2 == 0:
        sum = sum -i
    else:
        sum = sum + i
print(sum)

i = 1
sum = 0
while i < 100:
    if i % 2 == 0:
        sum = sum - i
    else:
        sum = sum + i
    i = i + 1
print(sum)


for i in range(10, -1, 1):
    print(i)