给定实数 x 和整数 n, 求 x的n次幂
时间复杂度：O(logN)
# !/usr/bin/env python
# -- coding: utf-8 --
# @Time : 2017/7/12 10:50
# @Author : Albert·Sun
# @Version : 0.10α-β
# @Description : None
def power(x, n):
if n == 0:
return 1
if n == 1:
return x
if n < 0:
return 1.0/power(x, -n)
if n % 2 == 0:
p = power(x, n/2)
return p*p
else:
p = power(x, (n-1)/2)
return x*p*p
if __name__ == "__main__":
print 'power(1.01, 365)', pow(1.01, 365), power(1.01, 365)
print 'power(0.99, 365)', pow(0.99, 365), power(0.99, 365)
print pow(0.99, -365), power(0.99, -365)
鸡汤.png
