50. Pow(x, n)

Problem Link

Description

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Implement pow(x, n), which calculates x raised to the power n (i.e., xn).

 

Example 1:

Input: x = 2.00000, n = 10
Output: 1024.00000

Example 2:

Input: x = 2.10000, n = 3
Output: 9.26100

Example 3:

Input: x = 2.00000, n = -2
Output: 0.25000
Explanation: 2-2 = 1/22 = 1/4 = 0.25

 

Constraints:

• -100.0 < x < 100.0
• -231 <= n <= 231-1
• n is an integer.
• Either x is not zero or n > 0.
• -104 <= xn <= 104

Solution

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Python3

class Solution:
    def myPow(self, x: float, n: int) -> float:
        if n < 0:
            n = -n
            x = 1 / x
 
        def p(base, k):
            if k == 0: return 1
 
            res = p(base, k // 2)
 
            if k % 2 == 0:
                return res * res
            else:
                return res * res * base
        
        return p(x, n)