find-bottom-left-tree-value

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Algorithms

You are given the <code>root</code> of a binary tree.

Return the leftmost value in the last row of the tree.

&nbsp;
Example 1:
<img alt="" src="https://assets.leetcode.com/uploads/2020/12/14/tree1.jpg" style="width: 302px; height: 182px;" />
<pre>
Input: root = [2,1,3]
Output: 1
Explanation: The last row is [1,3], so the leftmost value is 1.
</pre>

Example 2:
<img alt="" src="https://assets.leetcode.com/uploads/2020/12/14/tree2.jpg" style="width: 432px; height: 421px;" />
<pre>
Input: root = [1,2,3,4,null,5,6,null,null,7]
Output: 7
Explanation: The last row contains only the node 7.
</pre>

&nbsp;
Constraints:

<ul>
	<li>The number of nodes in the tree is in the range <code>[1, 104]</code>.</li>
	<li><code>-231 &lt;= Node.val &lt;= 231 - 1</code></li>
</ul>

findBottomLeftValue

Find Bottom Left Tree Value

Tree

Depth-First Search

Breadth-First Search

Binary Tree

给定一个二叉树的 根节点 <code>root</code>。

请找出该二叉树的&nbsp;最底层&nbsp;最左边&nbsp;节点的值。

&nbsp;

示例 1:

<img src="https://assets.leetcode.com/uploads/2020/12/14/tree1.jpg" style="width: 182px; " />

<pre>
输入：root = [2,1,3]
输出：1
解释：最后一行是 [1, 3]，因此最左边的值是 1。
</pre>

示例 2:

<img src="https://assets.leetcode.com/uploads/2020/12/14/tree2.jpg" style="width: 242px; " /> 

<pre>
输入：[1,2,3,4,null,5,6,null,null,7]
输出：7
解释：最后一层只有节点 7。</pre>

&nbsp;

提示:

<ul>
	<li>二叉树的节点个数的范围是 <code>[1, 104]</code></li>
	<li><meta charset="UTF-8" /><code>-231&nbsp;&lt;= Node.val &lt;= 231&nbsp;- 1</code>&nbsp;</li>
</ul>