[Feature] add for new

Author: binbin.hou

README.md

@@ -84,9 +84,10 @@ leetcode 算法笔记。
 
 # 101-200
 
-| 序号  | 难题                                                                                                       | 解决方案                                                                                                         | 速度% & 内存%                                                                                             | 时间                 | 难度   |
-|:----|:---------------------------------------------------------------------------------------------------------|:-------------------------------------------------------------------------------------------------------------|:------------------------------------------------------------------------------------------------------|:-------------------|:-----|
-| 101 | [symmetric-tree](doc/101-200/101-symmetric-tree.md)                                                      | [java](https://github.com/houbb/leetcode/blob/master/src/main/java/com/github/houbb/leetcode/F100T200/T101_SymmetricTree.java) | [100 & 88.82](https://leetcode.com/problems/symmetric-tree/submissions/870298167/)                    | 2023-1-3 16:08:16  | EASY |
-| 102 | [binary-tree-level-order-traversal](doc/101-200/102-binary-tree-level-order-traversal.md)                | [java](https://github.com/houbb/leetcode/blob/master/src/main/java/com/github/houbb/leetcode/F100T200/T102_BinaryTreeLevelOrderTraversal.java) | [100 & 99.99](https://leetcode.com/problems/binary-tree-level-order-traversal/submissions/468533749/) | 2021-3-16 21:37:16 | MEDIUM  |
-| 103 | [binary-tree-zigzag-level-order-traversal](doc/101-200/103-binary-tree-zigzag-level-order-traversal.md)  | [java](https://github.com/houbb/leetcode/blob/master/src/main/java/com/github/houbb/leetcode/F100T200/T103_BinaryTreeZigZagLevelOrderTraversal.java) | [100 & 99.99](https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/submissions/468942448/) | 2021-3-17 19:54:16 | MEDIUM  |
+| 序号  | 难题                                                                                                       | 解决方案                                                                                                         | 速度% & 内存%                                                                                                    | 时间                  | 难度   |
+|:----|:---------------------------------------------------------------------------------------------------------|:-------------------------------------------------------------------------------------------------------------|:-------------------------------------------------------------------------------------------------------------|:--------------------|:-----|
+| 101 | [symmetric-tree](doc/101-200/101-symmetric-tree.md)                                                      | [java](https://github.com/houbb/leetcode/blob/master/src/main/java/com/github/houbb/leetcode/F100T200/T101_SymmetricTree.java) | [100 & 88.82](https://leetcode.com/problems/symmetric-tree/submissions/870298167/)                           | 2023-01-03 16:08:16 | EASY |
+| 102 | [binary-tree-level-order-traversal](doc/101-200/102-binary-tree-level-order-traversal.md)                | [java](https://github.com/houbb/leetcode/blob/master/src/main/java/com/github/houbb/leetcode/F100T200/T102_BinaryTreeLevelOrderTraversal.java) | [100 & 99.99](https://leetcode.com/problems/binary-tree-level-order-traversal/submissions/468533749/)        | 2021-03-16 21:37:16 | MEDIUM  |
+| 103 | [binary-tree-zigzag-level-order-traversal](doc/101-200/103-binary-tree-zigzag-level-order-traversal.md)  | [java](https://github.com/houbb/leetcode/blob/master/src/main/java/com/github/houbb/leetcode/F100T200/T103_BinaryTreeZigZagLevelOrderTraversal.java) | [100 & 99.98](https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/submissions/468942448/) | 2021-03-17 19:54:16 | MEDIUM  |
+| 104 | [maximum-depth-of-binary-tree](doc/101-200/104-maximum-depth-of-binary-tree.md)  | [java](https://github.com/houbb/leetcode/blob/master/src/main/java/com/github/houbb/leetcode/F100T200/T104_MaximumDepthOfBinaryTree.java) | [100 & 42.64](https://leetcode.com/problems/maximum-depth-of-binary-tree/submissions/870313682/)             | 2023-01-03 16:42:16 | EASY  |
 

doc/101-200/104-maximum-depth-of-binary-tree.md

@@ -0,0 +1,30 @@
+https://leetcode.com/problems/maximum-depth-of-binary-tree/description/
+
+# 104. Maximum Depth of Binary Tree
+
+Given the root of a binary tree, return its maximum depth.
+
+A binary tree's maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.
+
+# Example
+
+example 1:
+
+![ex1](https://assets.leetcode.com/uploads/2020/11/26/tmp-tree.jpg)
+
+```
+Input: root = [3,9,20,null,null,15,7]
+Output: 3
+```
+
+example 2:
+
+```
+Input: root = [1,null,2]
+Output: 2
+```
+
+# Constraints:
+
+    The number of nodes in the tree is in the range [0, 10^4].
+    -100 <= Node.val <= 100

src/main/java/com/github/houbb/leetcode/F100T200/T104_MaximumDepthOfBinaryTree.java

@@ -0,0 +1,25 @@
+package com.github.houbb.leetcode.F100T200;
+
+import com.github.houbb.leetcode.component.TreeNode;
+
+/**
+ * 思路：
+ *
+ * 1. 遍历一棵树，然后到最后一层，就是最大的长度
+ * 2. 应该使用哪一种遍历？
+ */
+public class T104_MaximumDepthOfBinaryTree {
+
+    public int maxDepth(TreeNode root) {
+        if(root == null) {
+            return 0;
+        }
+
+        // 递归左右
+        // 递归真的是神！
+        return Math.max(maxDepth(root.left), maxDepth(root.right)) + 1;
+    }
+
+
+
+}