50. Pow\(x, n\)

2019-04-28

50. Pow(x, n)

Implement pow(_x_, _n_), which calculates _x_ raised to the power _n_ (xn).

Example 1:

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Input: 2.00000, 10
Output: 1024.00000

Example 2:

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Input: 2.10000, 3
Output: 9.26100

Example 3:

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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]

Code:

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class Solution(object):
    def myPow(self, x, n):
        """
        :type x: float
        :type n: int
        :rtype: float
        """
        if n == 0:
            return 1.0
        elif n < 0:
            return 1 / self.myPow(x, -n)
        elif n % 2:
            return self.myPow(x*x,n/2)*x
        else:
            return self.myPow(x*x,n/2)
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