Implement pow(x, n), which calculates x raised to the power n (i.e., x^n).
Input: x = 2.00000, n = 10 Output: 1024.00000 Explanation: 2^10 = 1024.
Input: x = 2.10000, n = 3 Output: 9.26100 Explanation: 2.1^3 = 9.261.
Input: x = 2.00000, n = -2 Output: 0.25000 Explanation: 2^(-2) = 1 / 2^2 = 0.25.
-100.0 < x < 100.0-2^31 <= n <= 2^31 - 1n is an integer.x is not zero, or n > 0.-10^4 <= x^n <= 10^4x = 2.0, n = 10