leetcode-problemset/算法题（国内版）/problem (Chinese)/二叉树每层的最大值 [hPov7L].html

<p>给定一棵二叉树的根节点&nbsp;<code>root</code> ，请找出该二叉树中每一层的最大值。</p>

<p>&nbsp;</p>

<p><strong>示例1：</strong></p>

<pre>
<strong>输入: </strong>root = [1,3,2,5,3,null,9]
<strong>输出: </strong>[1,3,9]
<strong>解释:</strong>
          1
         / \
        3   2
       / \   \  
      5   3   9 
</pre>

<p><strong>示例2：</strong></p>

<pre>
<strong>输入: </strong>root = [1,2,3]
<strong>输出: </strong>[1,3]
<strong>解释:</strong>
          1
         / \
        2   3
</pre>

<p><strong>示例3：</strong></p>

<pre>
<strong>输入: </strong>root = [1]
<strong>输出: </strong>[1]
</pre>

<p><strong>示例4：</strong></p>

<pre>
<strong>输入: </strong>root = [1,null,2]
<strong>输出: </strong>[1,2]
<strong>解释:</strong>      
&nbsp;          1 
&nbsp;           \
&nbsp;            2     
</pre>

<p><strong>示例5：</strong></p>

<pre>
<strong>输入: </strong>root = []
<strong>输出: </strong>[]
</pre>

<p>&nbsp;</p>

<p><strong>提示：</strong></p>

<ul>
	<li>二叉树的节点个数的范围是 <code>[0,10<sup>4</sup>]</code></li>
	<li><meta charset="UTF-8" /><code>-2<sup>31</sup>&nbsp;&lt;= Node.val &lt;= 2<sup>31</sup>&nbsp;- 1</code></li>
</ul>

<p>&nbsp;</p>

<p><meta charset="UTF-8" />注意：本题与主站 515&nbsp;题相同：&nbsp;<a href="https://leetcode-cn.com/problems/find-largest-value-in-each-tree-row/">https://leetcode-cn.com/problems/find-largest-value-in-each-tree-row/</a></p>