Pow(x, n)

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 = 0.25

Constraints:

• -100.0 < x < 100.0
• -2³¹ <= n <= 2³¹ - 1
• n is an integer
• Either x != 0 or n > 0
• -10⁴ <= xⁿ <= 10⁴