sum-of-left-leaves

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Algorithms

Given the <code>root</code> of a binary tree, return the sum of all left leaves.

A leaf is a node with no children. A left leaf is a leaf that is the left child of another node.

&nbsp;
Example 1:
<img alt="" src="https://assets.leetcode.com/uploads/2021/04/08/leftsum-tree.jpg" style="width: 277px; height: 302px;" />
<pre>
Input: root = [3,9,20,null,null,15,7]
Output: 24
Explanation: There are two left leaves in the binary tree, with values 9 and 15 respectively.
</pre>

Example 2:

<pre>
Input: root = [1]
Output: 0
</pre>

&nbsp;
Constraints:

<ul>
	<li>The number of nodes in the tree is in the range <code>[1, 1000]</code>.</li>
	<li><code>-1000 &lt;= Node.val &lt;= 1000</code></li>
</ul>

sumOfLeftLeaves

Sum of Left Leaves

Tree

Depth-First Search

Breadth-First Search

Binary Tree

给定二叉树的根节点&nbsp;<code>root</code>&nbsp;，返回所有左叶子之和。

&nbsp;

示例 1：

<img src="https://assets.leetcode.com/uploads/2021/04/08/leftsum-tree.jpg" />

<pre>
输入: root = [3,9,20,null,null,15,7] 
输出: 24 
解释: 在这个二叉树中，有两个左叶子，分别是 9 和 15，所以返回 24
</pre>

示例&nbsp;2:

<pre>
输入: root = [1]
输出: 0
</pre>

&nbsp;

提示:

<ul>
	<li>节点数在&nbsp;<code>[1, 1000]</code>&nbsp;范围内</li>
	<li><code>-1000 &lt;= Node.val &lt;= 1000</code></li>
</ul>

&nbsp;