mirror of
https://gitee.com/coder-xiaomo/leetcode-problemset
synced 2025-11-04 03:33:12 +08:00
35 lines
1.5 KiB
HTML
35 lines
1.5 KiB
HTML
<p>There is a street with <code>n * 2</code> <strong>plots</strong>, where there are <code>n</code> plots on each side of the street. The plots on each side are numbered from <code>1</code> to <code>n</code>. On each plot, a house can be placed.</p>
|
|
|
|
<p>Return <em>the number of ways houses can be placed such that no two houses are adjacent to each other on the same side of the street</em>. Since the answer may be very large, return it <strong>modulo</strong> <code>10<sup>9</sup> + 7</code>.</p>
|
|
|
|
<p>Note that if a house is placed on the <code>i<sup>th</sup></code> plot on one side of the street, a house can also be placed on the <code>i<sup>th</sup></code> plot on the other side of the street.</p>
|
|
|
|
<p> </p>
|
|
<p><strong class="example">Example 1:</strong></p>
|
|
|
|
<pre>
|
|
<strong>Input:</strong> n = 1
|
|
<strong>Output:</strong> 4
|
|
<strong>Explanation:</strong>
|
|
Possible arrangements:
|
|
1. All plots are empty.
|
|
2. A house is placed on one side of the street.
|
|
3. A house is placed on the other side of the street.
|
|
4. Two houses are placed, one on each side of the street.
|
|
</pre>
|
|
|
|
<p><strong class="example">Example 2:</strong></p>
|
|
<img alt="" src="https://assets.leetcode.com/uploads/2022/05/12/arrangements.png" style="width: 500px; height: 500px;" />
|
|
<pre>
|
|
<strong>Input:</strong> n = 2
|
|
<strong>Output:</strong> 9
|
|
<strong>Explanation:</strong> The 9 possible arrangements are shown in the diagram above.
|
|
</pre>
|
|
|
|
<p> </p>
|
|
<p><strong>Constraints:</strong></p>
|
|
|
|
<ul>
|
|
<li><code>1 <= n <= 10<sup>4</sup></code></li>
|
|
</ul>
|