projecteuler_欧拉几何问题（1~10题）

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练习自己的code能力，完成projecteuler的题目，做一个归档记录。

第1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.

找出1000以下，可以整除3或者5的数，并计算出它们的和。

#!/usr/bin/env python
# -*- coding: utf-8 -*-  

def Multiples_of_3_and_5(num):
    sum=0
    for n in xrange(num):
        if not n%3 or not n%5:
            sum+=n
    return sum

if __name__ == "__main__":
    print Multiples_of_3_and_5(1000)

第2题：

Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:

1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...

By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.

一个斐波那契数列，以1和2开始。求出不大于四百万的偶数的和。

#!/usr/bin/env python
# -*- coding: utf-8 -*-  

def fib():
    x,y=1,2
    sum=2           #这里是偶数的和，所以初始sum为2
    while sum<4000000:
        x,y=y,x+y
        if not y%2:
            sum+=y
    return sum
 
if __name__ == "__main__":   
    print fib()