Implement pow(x, n), which calculates x raised to the power n (i.e., x^n).
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
Constraints:
- -100.0 < x < 100.0
- -2^31 <= n <= 2^31 - 1