用python测试代码的运行时间

　原题:

If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.

Find the sum of all the multiples of 3 or 5 below 1000.

测试代码:

from time import clock as now

def getNatureSum(beg , max):

n = max / beg

end = beg * n

return (beg + end) * n / 2

def getSum(max) :

print getNatureSum( 3 , max ) + getNatureSum( 5 , max) - getNatureSum(15 , max)

start = now()

getSum(999)

finish = now()

print (finish-start)

改进后的代码:

from time import clock as now

start = now()

a = range(3 , 1000 , 3)

b = range(5 , 1000 , 5)

c = range(15 , 1000 , 15)

print sum(a) + sum(b) - sum(c)

finish = now()

print (finish-start)