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(object):
def myPow(self, x, n):
"""
:type x: float
:type n: int
:rtype: float
"""
def helper(x, n):
if n == 0: return 1.0
h = helper(x, n // 2)
if (n % 2 == 0): return h * h
else: return h * h * x
if n >= 0: return helper(x, n)
return 1 / helper(x, -n)