commit solution 104

Author: lxlxw

Diff for: index-tags.md

@@ -141,6 +141,7 @@
 | --- | --- | --- | --- | --- |
 |  [100](https://leetcode-cn.com/problems/same-tree)  |  [相同的树](/solution/100-199/0100.same-tree/)  |  `树`,`深度优先搜索`  |  <font color=green>简单</font>  |✅ |
 |  [101](https://leetcode-cn.com/problems/symmetric-tree)  |  [对称二叉树](/solution/100-199/0101.symmetric-tree/)  |  `树`,`深度优先搜索`,`广度优先搜索`  |  <font color=green>简单</font>  |✅ |
+|  [104](https://leetcode-cn.com/problems/maximum-depth-of-binary-tree)  |  [二叉树的最大深度](/solution/100-199/0104.maximum-depth-of-binary-tree/)  |  `树`,`深度优先搜索`  |  <font color=green>简单</font>  |✅ |
 
 #### **递归**
 
@@ -150,6 +151,7 @@
 | --- | --- | --- | --- | --- |
 |  [100](https://leetcode-cn.com/problems/same-tree)  |  [相同的树](/solution/100-199/0100.same-tree/)  |  `树`,`深度优先搜索`  |  <font color=green>简单</font>  |✅ |
 |  [101](https://leetcode-cn.com/problems/symmetric-tree)  |  [对称二叉树](/solution/100-199/0101.symmetric-tree/)  |  `树`,`深度优先搜索`,`广度优先搜索`  |  <font color=green>简单</font>  |✅ |
+|  [104](https://leetcode-cn.com/problems/maximum-depth-of-binary-tree)  |  [二叉树的最大深度](/solution/100-199/0104.maximum-depth-of-binary-tree/)  |  `树`,`深度优先搜索`  |  <font color=green>简单</font>  |✅ |
 
 #### **广度优先搜索**
 

Diff for: index-type.md

@@ -29,7 +29,7 @@
 |  [88](https://leetcode-cn.com/problems/merge-sorted-array)  |  [合并两个有序数组](/solution/1-99/0088.merge-sorted-array/)  |  `数组`,`双指针`  |  <font color=green>简单</font>  |✅ |
 |  [100](https://leetcode-cn.com/problems/same-tree)  |  [相同的树](/solution/100-199/0100.same-tree/)  |  `树`,`深度优先搜索`  |  <font color=green>简单</font>  |✅ |
 |  [101](https://leetcode-cn.com/problems/symmetric-tree)  |  [对称二叉树](/solution/100-199/0101.symmetric-tree/)  |  `树`,`深度优先搜索`,`广度优先搜索`  |  <font color=green>简单</font>  |✅ |
-|  [104](https://leetcode-cn.com/problems/maximum-depth-of-binary-tree)  |  [二叉树的最大深度](/solution/100-199/0104.maximum-depth-of-binary-tree/)  |  `树`,`深度优先搜索`  |  <font color=green>简单</font>  |
+|  [104](https://leetcode-cn.com/problems/maximum-depth-of-binary-tree)  |  [二叉树的最大深度](/solution/100-199/0104.maximum-depth-of-binary-tree/)  |  `树`,`深度优先搜索`  |  <font color=green>简单</font>  |✅ |
 |  [107](https://leetcode-cn.com/problems/binary-tree-level-order-traversal-ii)  |  [二叉树的层次遍历 ii](/solution/100-199/0107.binary-tree-level-order-traversal-ii/)  |  `树`,`广度优先搜索`  |  <font color=green>简单</font>  |
 |  [108](https://leetcode-cn.com/problems/convert-sorted-array-to-binary-search-tree)  |  [将有序数组转换为二叉搜索树](/solution/100-199/0108.convert-sorted-array-to-binary-search-tree/)  |  `树`,`深度优先搜索`  |  <font color=green>简单</font>  |
 |  [110](https://leetcode-cn.com/problems/balanced-binary-tree)  |  [平衡二叉树](/solution/100-199/0110.balanced-binary-tree/)  |  `树`,`深度优先搜索`  |  <font color=green>简单</font>  |

Diff for: solution/100-199/0104.maximum-depth-of-binary-tree/README.md

@@ -1,19 +1,45 @@
-# [100. xxx](https://leetcode-cn.com/problems/recover-binary-search-tree)
+# [104. 二叉树的最大深度](https://leetcode-cn.com/problems/maximum-depth-of-binary-tree/description/)
 
 ### 题目描述
 
+<p>给定一个二叉树，找出其最大深度。</p>
+
+<p>二叉树的深度为根节点到最远叶子节点的最长路径上的节点数。</p>
+
+<p><strong>说明:</strong>&nbsp;叶子节点是指没有子节点的节点。</p>
+
+<p><strong>示例：</strong><br>
+给定二叉树 <code>[3,9,20,null,null,15,7]</code>，</p>
+
+<pre>    3
+   / \
+  9  20
+    /  \
+   15   7</pre>
+
+<p>返回它的最大深度&nbsp;3 。</p>
 
 ### 解题思路
 
+1. 分治
 
 ### 具体解法
 
-<!-- tabs:start -->
-
 #### **Golang**
 ```go
-
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+func maxDepth(root *TreeNode) int {
+	if root == nil {
+		return 0
+	}
+	left := maxDepth(root.Left)
+	right := maxDepth(root.Right)
+	return 1 + int(math.Max(float64(left), float64(right)))
+}
 ```
 
-<!-- tabs:end -->
-

Diff for: solution/100-199/0104.maximum-depth-of-binary-tree/solution.go

@@ -0,0 +1,35 @@
+package leetcode
+
+import "math"
+
+/*
+ * @lc app=leetcode.cn id=104 lang=golang
+ *
+ * [104] 二叉树的最大深度
+ */
+
+// @lc code=start
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+func maxDepth(root *TreeNode) int {
+	if root == nil {
+		return 0
+	}
+	left := maxDepth(root.Left)
+	right := maxDepth(root.Right)
+	return 1 + int(math.Max(float64(left), float64(right)))
+}
+
+// @lc code=end

Diff for: solution/100-199/0104.maximum-depth-of-binary-tree/solution_test.go

@@ -0,0 +1,40 @@
+package leetcode
+
+import (
+	"testing"
+)
+
+func TestMaxDepth(t *testing.T) {
+	var ret int
+	p := &TreeNode{
+		Val: 2,
+		Left: &TreeNode{
+			Val: 3,
+			Left: &TreeNode{
+				Val:   4,
+				Left:  nil,
+				Right: nil,
+			},
+			Right: &TreeNode{
+				Val:   5,
+				Left:  nil,
+				Right: nil,
+			},
+		},
+		Right: &TreeNode{
+			Val:  3,
+			Left: nil,
+			Right: &TreeNode{
+				Val:   4,
+				Left:  nil,
+				Right: nil,
+			},
+		},
+	}
+
+	ret = 3
+	if ret != maxDepth(p) {
+		t.Fatalf("case fails %v\n", ret)
+	}
+
+}

Diff for: solution/100-199/_sidebar.md

@@ -10,7 +10,7 @@
     - [101. 对称二叉树 ✅](solution/100-199/0101.symmetric-tree/)
     - [102. 二叉树的层序遍历](solution/100-199/0102.binary-tree-level-order-traversal/)
     - [103. 二叉树的锯齿形层次遍历](solution/100-199/0103.binary-tree-zigzag-level-order-traversal/)
-    - [104. 二叉树的最大深度](solution/100-199/0104.maximum-depth-of-binary-tree/)
+    - [104. 二叉树的最大深度 ✅](solution/100-199/0104.maximum-depth-of-binary-tree/)
     - [105. 从前序与中序遍历序列构造二叉树](solution/100-199/0105.construct-binary-tree-from-preorder-and-inorder-traversal/)
     - [106. 从中序与后序遍历序列构造二叉树](solution/100-199/0106.construct-binary-tree-from-inorder-and-postorder-traversal/)
     - [107. 二叉树的层次遍历 ii](solution/100-199/0107.binary-tree-level-order-traversal-ii/)