[Leetcode] 50. Pow(x, n) @python
2016-01-18 20:58
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题目
Implement pow(x, n).题目要求
实现x的n次幂。解题思路
此题参考南郭子綦自己想了很久,没想到用这么几行代码就搞定了。
采用递归来实现二分。分以下四种情况考虑:
1. n ==0 ,返回1.0
2. n < 0, 返回1/pow(x,-n)
3. n % 2 == 0,返回pow(x*x,n/2)
4. n % 2 == 1,返回pow(x*x,n/2) * x$
代码
class Solution(object): def myPow(self, x, n): """ :type x: float :type n: int :rtype: float """ if n == 0: return 1.0 if n < 0: return 1 / self.myPow(x,-n) if n % 2 == 0: return self.myPow(x*x,n/2) else: return self.myPow(x*x,n/2) * x
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