Feat: 104

FX-Max · FX-Max · commit 793a1512a657 · 2021-11-11T00:26:43.000+08:00
diff --git a/problems/104-maximum-depth-of-binary-tree.md b/problems/104-maximum-depth-of-binary-tree.md
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+## 题目
+
+* 104. 二叉树的最大深度
+
+给定一个二叉树，找出其最大深度。
+
+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。
+
+说明: 叶子节点是指没有子节点的节点。
+
+## 思路
+
+
+
+## 代码
+
+```php
+/**
+ * Definition for a binary tree node.
+ * class TreeNode {
+ *     public $val = null;
+ *     public $left = null;
+ *     public $right = null;
+ *     function __construct($val = 0, $left = null, $right = null) {
+ *         $this->val = $val;
+ *         $this->left = $left;
+ *         $this->right = $right;
+ *     }
+ * }
+ */
+class Solution {
+
+    /**
+     * @param TreeNode $root
+     * @return Integer
+     */
+    function maxDepth($root) {
+        if (!$root) {
+            return 0;
+        }
+        $leftDepth = $this->maxDepth($root->left);
+        $rightDepth = $this->maxDepth($root->right);
+        return max($leftDepth, $rightDepth) + 1;
+    }
+}
+
+```
+
