# [404. Sum of Left Leaves](https://leetcode.com/problems/sum-of-left-leaves/)


## 题目

Find the sum of all left leaves in a given binary tree.

**Example:**

        3
       / \
      9  20
        /  \
       15   7
    
    There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24.


## 题目大意

计算给定二叉树的所有左叶子之和。


## 解题思路


- 这一题是微软的面试题。递归求解即可