add youtube link for 104

fishercoder1534 · fishercoder1534 · commit 2aeb8a3ce5ef · 2020-02-20T06:36:50.000-08:00
diff --git a/README.md b/README.md
@@ -792,7 +792,7 @@ _If you like this project, please leave me a star._ &#9733;
 |107|[Binary Tree Level Order Traversal II](https://leetcode.com/problems/binary-tree-level-order-traversal-ii/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_107.java)|  |Easy| BFS
 |106|[Construct Binary Tree from Inorder and Postorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_106.java)|  |Medium| Recursion, Tree
 |105|[Construct Binary Tree from Preorder and Inorder Traversal](https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_105.java)|  |Medium| Recursion, Tree 
-|104|[Maximum Depth of Binary Tree](https://leetcode.com/problems/maximum-depth-of-binary-tree/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_104.java)|  |Easy| DFS
+|104|[Maximum Depth of Binary Tree](https://leetcode.com/problems/maximum-depth-of-binary-tree/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_104.java)| [:tv:](https://youtu.be/dvmoHr5cN80) |Easy| DFS
 |103|[Binary Tree Zigzag Level Order Traversal](https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_103.java)| |Medium| BFS,DFS
 |102|[Binary Tree Level Order Traversal](https://leetcode.com/problems/binary-tree-level-order-traversal/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_102.java)|  |Medium| BFS
 |101|[Symmetric Tree](https://leetcode.com/problems/symmetric-tree/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_101.java)| [:tv:](https://www.youtube.com/watch?v=F85boSPtfKg)|Easy| DFS
