Project Euler Problem 1 Python Version

Project Euler Problem 1.py

# coding: Shift_JIS
 
#単純に加算
sum = 0
for i in range(1, 1000):
    if i % 3 == 0:
        sum += i
    elif i % 5 == 0:
        sum += i
print sum
 
#等差数列の和
sum = 0
#初項, 公差
for a in [3, 5, 15]:
    n = int(999 / a) #項数
    l = n * a        #末項 a＋(n－1)d
 
    if a == 3 or a == 5:
        sum += ((a + l) * n / 2)
    else:
        sum -= ((a + l) * n / 2)
print sum