Add 0404-sum-of-left-leaves to topics.

Author: shimhun99

README.md

@@ -9,6 +9,7 @@
 | [0111-minimum-depth-of-binary-tree](https://github.com/SHIMHUN/Algorithm/tree/main/LeetCode/Easy/0111-minimum-depth-of-binary-tree/) | Easy |
 | [0112-path-sum](https://github.com/SHIMHUN/Algorithm/tree/main/LeetCode/Easy/0112-path-sum/) | Easy |
 | [0226-invert-binary-tree](https://github.com/SHIMHUN/Algorithm/tree/main/LeetCode/Easy/0226-invert-binary-tree/) | Easy |
+| [0404-sum-of-left-leaves](https://github.com/SHIMHUN/Algorithm/tree/main/LeetCode/Easy/0404-sum-of-left-leaves/) | Easy |
 ## Depth-First Search
 | Problem Name | Difficulty |
 | ------- | ------- |
@@ -17,6 +18,7 @@
 | [0111-minimum-depth-of-binary-tree](https://github.com/SHIMHUN/Algorithm/tree/main/LeetCode/Easy/0111-minimum-depth-of-binary-tree/) | Easy |
 | [0112-path-sum](https://github.com/SHIMHUN/Algorithm/tree/main/LeetCode/Easy/0112-path-sum/) | Easy |
 | [0226-invert-binary-tree](https://github.com/SHIMHUN/Algorithm/tree/main/LeetCode/Easy/0226-invert-binary-tree/) | Easy |
+| [0404-sum-of-left-leaves](https://github.com/SHIMHUN/Algorithm/tree/main/LeetCode/Easy/0404-sum-of-left-leaves/) | Easy |
 ## Breadth-First Search
 | Problem Name | Difficulty |
 | ------- | ------- |
@@ -25,6 +27,7 @@
 | [0111-minimum-depth-of-binary-tree](https://github.com/SHIMHUN/Algorithm/tree/main/LeetCode/Easy/0111-minimum-depth-of-binary-tree/) | Easy |
 | [0112-path-sum](https://github.com/SHIMHUN/Algorithm/tree/main/LeetCode/Easy/0112-path-sum/) | Easy |
 | [0226-invert-binary-tree](https://github.com/SHIMHUN/Algorithm/tree/main/LeetCode/Easy/0226-invert-binary-tree/) | Easy |
+| [0404-sum-of-left-leaves](https://github.com/SHIMHUN/Algorithm/tree/main/LeetCode/Easy/0404-sum-of-left-leaves/) | Easy |
 ## Binary Tree
 | Problem Name | Difficulty |
 | ------- | ------- |
@@ -33,4 +36,5 @@
 | [0111-minimum-depth-of-binary-tree](https://github.com/SHIMHUN/Algorithm/tree/main/LeetCode/Easy/0111-minimum-depth-of-binary-tree/) | Easy |
 | [0112-path-sum](https://github.com/SHIMHUN/Algorithm/tree/main/LeetCode/Easy/0112-path-sum/) | Easy |
 | [0226-invert-binary-tree](https://github.com/SHIMHUN/Algorithm/tree/main/LeetCode/Easy/0226-invert-binary-tree/) | Easy |
+| [0404-sum-of-left-leaves](https://github.com/SHIMHUN/Algorithm/tree/main/LeetCode/Easy/0404-sum-of-left-leaves/) | Easy |
 <!---LeetCode Topics End-->