</p>

<h1>include</h1>

<p>using namespace std;
int main()
{
    int n; // 菱形最长行的<em>的个数为n，且n一定为奇数因为 n = 2</em>k + 1
    cin &amp;gt;&amp;gt; n;</p>

<pre><code>int cn = 1;
bool isUp = true;
for (int i = 1;i    {
    for (int j = 1; j       {
        cout &amp;amp;lt;&amp;amp;lt; &amp;amp;quot; &amp;amp;quot;;
    }
    for (int j = 1; j       {
        cout &amp;amp;lt;&amp;amp;lt; &amp;amp;quot;*&amp;amp;quot;;
    }
    for (int j = 1; j       {
        cout &amp;amp;lt;&amp;amp;lt; &amp;amp;quot; &amp;amp;quot;;
    }
    cout &amp;amp;lt;&amp;amp;lt; endl;         if (cn &amp;amp;gt;= n)
    {
        isUp = false;
    }
    if (isUp)
    {
        cn += 2;
    }
    else
    {
        cn -= 2;
    }
}
return 0;
</code></pre>

<p>}