Paint Fence
<p>You are painting a fence of <code>n</code> posts with <code>k</code> different colors. You must paint the posts following these rules:</p>

<ul>
	<li>Every post must be painted <strong>exactly one</strong> color.</li>
	<li>There <strong>cannot</strong> be three or more <strong>consecutive</strong> posts with the same color.</li>
</ul>

<p>Given the two integers <code>n</code> and <code>k</code>, return <em>the <strong>number of ways</strong> you can paint the fence</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/0200-0299/0276.Paint%20Fence/images/paintfenceex1.png" style="width: 507px; height: 313px;" />
<pre>
<strong>Input:</strong> n = 3, k = 2
<strong>Output:</strong> 6
<strong>Explanation: </strong>All the possibilities are shown.
Note that painting all the posts red or all the posts green is invalid because there cannot be three posts in a row with the same color.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> n = 1, k = 1
<strong>Output:</strong> 1
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> n = 7, k = 2
<strong>Output:</strong> 42
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= n &lt;= 50</code></li>
	<li><code>1 &lt;= k &lt;= 10<sup>5</sup></code></li>
	<li>The testcases are generated such that the answer is in the range <code>[0, 2<sup>31</sup> - 1]</code> for the given <code>n</code> and <code>k</code>.</li>
</ul>
Dynamic Programming
func numWays(n int, k int) int {
	f := make([]int, n)
	g := make([]int, n)
	f[0] = k
	for i := 1; i < n; i++ {
		f[i] = (f[i-1] + g[i-1]) * (k - 1)
		g[i] = f[i-1]
	}
	return f[n-1] + g[n-1]
}