愚蠢的求素數

import math
import time

def BySqrt(a,b):
    numList = list()
    flag = 0
    for i in range(a,b):
        for j in range(2, int(math.sqrt(i)) + 1):
            if i % j == 0:
                flag = 1
                break
            else:
                flag = 0
        if flag == 0:
            numList.append(i)
    return numList

for num in BySqrt(1,100):
    print num

start = time.clock()
end = time.clock()
print end-start

求和

def AddUp(a,b):
    s = 0
    for i in range(a,b):
        s=s+i
    return s

print AddUp(1,100)