diff --git a/src/main/java/leetcode/editor/cn/MaximumDepthOfBinaryTree.java b/src/main/java/leetcode/editor/cn/MaximumDepthOfBinaryTree.java
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+//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。 
+//
+// 示例： 
+//给定二叉树 [3,9,20,null,null,15,7]， 
+//
+//     3
+//   / \
+//  9  20
+//    /  \
+//   15   7 
+//
+// 返回它的最大深度 3 。 
+// Related Topics 树 深度优先搜索 广度优先搜索 二叉树 👍 1012 👎 0
+
+package leetcode.editor.cn;
+
+import com.code.leet.entiy.TreeNode;
+
+import java.util.LinkedList;
+import java.util.Queue;
+
+//104:二叉树的最大深度
+class MaximumDepthOfBinaryTree {
+    public static void main(String[] args) {
+        //测试代码
+        Solution solution = new MaximumDepthOfBinaryTree().new Solution();
+    }
+
+    //力扣代码
+    //leetcode submit region begin(Prohibit modification and deletion)
+
+    /**
+     * Definition for a binary tree node.
+     * public class TreeNode {
+     * int val;
+     * TreeNode left;
+     * TreeNode right;
+     * TreeNode() {}
+     * TreeNode(int val) { this.val = val; }
+     * TreeNode(int val, TreeNode left, TreeNode right) {
+     * this.val = val;
+     * this.left = left;
+     * this.right = right;
+     * }
+     * }
+     */
+    class Solution {
+        public int maxDepth(TreeNode root) {
+            if (root == null) {
+                return 0;
+            }
+            Queue<TreeNode> queue = new LinkedList<>();
+            queue.add(root);
+            int count = 0;
+            while (!queue.isEmpty()) {
+                int size = queue.size();
+                if (size > 0) {
+                    count++;
+                }
+                for (int i = 0; i < size; i++) {
+                    TreeNode node = queue.poll();
+                    assert node != null;
+                    if (node.left != null) {
+                        queue.add(node.left);
+                    }
+                    if (node.right != null) {
+                        queue.add(node.right);
+                    }
+                }
+            }
+            return count;
+        }
+    }
+//leetcode submit region end(Prohibit modification and deletion)
+
+}
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diff --git a/src/main/java/leetcode/editor/cn/doc/content/MaximumDepthOfBinaryTree.md b/src/main/java/leetcode/editor/cn/doc/content/MaximumDepthOfBinaryTree.md
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+<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>
+<div><div>Related Topics</div><div><li>树</li><li>深度优先搜索</li><li>广度优先搜索</li><li>二叉树</li></div></div><br><div><li>👍 1012</li><li>👎 0</li></div>
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