mirror of
https://gitee.com/coder-xiaomo/leetcode-problemset
synced 2025-01-11 02:58:13 +08:00
22 lines
608 B
HTML
22 lines
608 B
HTML
<p>A child is running up a staircase with n steps and can hop either 1 step, 2 steps, or 3 steps at a time. Implement a method to count how many possible ways the child can run up the stairs. The result may be large, so return it modulo 1000000007.</p>
|
|
|
|
|
|
|
|
<p><strong>Example1:</strong></p>
|
|
|
|
|
|
|
|
<pre>
|
|
|
|
<strong> Input</strong>: n = 3
|
|
|
|
<strong> Output</strong>: 4
|
|
|
|
</pre>
|
|
|
|
|
|
|
|
<p><strong>Example2:</strong></p>
|
|
|
|
|
|
|
|
<pre>
|
|
|
|
<strong> Input</strong>: n = 5
|
|
|
|
<strong> Output</strong>: 13
|
|
|
|
</pre>
|
|
|
|
|
|
|
|
<p><strong>Note:</strong></p>
|
|
|
|
|
|
|
|
<ol>
|
|
|
|
<li><code>1 <= n <= 1000000</code></li>
|
|
|
|
</ol>
|
|
|