原理可参考：https://blog.csdn.net/qq_19782019/article/details/85621386

'''
@param base 底数
@param power 指数
@return res 求幂结果的最后3位数 
'''
def fast_power(base, power):
    res = 1
    while power > 0:
        if power % 2 == 1:
            res = res * base % 1000
        power = power // 2
        base = base * base % 1000
    return res % 1000
print(fast_power(2,1000000000))