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myPow.py
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myPow.py
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# -*- coding: utf-8 -*-
"""
@author : zenithude
Implement pow(x, n), which calculates x raised to the power n (xn).
Example 1:
Input: 2.00000, 10
Output: 1024.00000
Example 2:
Input: 2.10000, 3
Output: 9.26100
Example 3:
Input: 2.00000, -2
Output: 0.25000
Explanation: 2-2 = 1/22 = 1/4 = 0.25
Note:
-100.0 < x < 100.0
n is a 32-bit signed integer, within the range [−231, 231 − 1]
"""
class Solution:
def myPow(self, x: float, n: int) -> float:
"""
:param x: float
:param n: int
:return: float
"""
if x == 0 or x == 1 or n == 1:
return x
if x == -1:
if n % 2 == 0:
return 1.0
else:
return -1.0
if n == 0:
return 1.0
if n < 0:
return 1 / self.myPow(x, -n)
val = self.myPow(x, n // 2)
if n % 2 == 0:
return val * val
return val * val * x
obj = Solution()
print(obj.myPow(2.0, -4))
print(pow(2.0, -4))