# 50. Pow(x, n)

## Medium

***

Implement [pow(x, n)](http://www.cplusplus.com/reference/valarray/pow/), 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`
* `-104 <= xn <= 104`