diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index 5113939..46b8313 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -2,7 +2,9 @@
 <project version="4">
   <component name="ChangeListManager">
     <list default="true" id="af7ffdf2-4ddc-4ed6-8222-60ed5acbc2ed" name="Default Changelist" comment="">
-      <change afterPath="$PROJECT_DIR$/src/数组操作/q945_使数组唯一的最小增量/Solution.java" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/src/动态规划/q70_爬楼梯/Solution.java" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/src/递归/q104_二叉树的最大深度/Solution.java" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/src/递归/q104_二叉树的最大深度/TreeNode.java" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/README.md" beforeDir="false" afterPath="$PROJECT_DIR$/README.md" afterDir="false" />
     </list>
@@ -67,11 +69,11 @@
   </component>
   <component name="RecentsManager">
     <key name="CopyClassDialog.RECENTS_KEY">
+      <recent name="递归.q104_二叉树的最大深度" />
       <recent name="快慢指针遍历.q876_链表的中间结点" />
       <recent name="递归.q226_翻转二叉树" />
       <recent name="链表操作.q138_复制带随机指针的链表.f2" />
       <recent name="链表操作.q138_复制带随机指针的链表.f1" />
-      <recent name="hash相关.q141_环形链表.f2" />
     </key>
     <key name="CopyFile.RECENT_KEYS">
       <recent name="$PROJECT_DIR$/src/hash相关" />
@@ -288,14 +290,7 @@
       <workItem from="1584416544436" duration="218000" />
       <workItem from="1584977075044" duration="499000" />
       <workItem from="1585037684584" duration="753000" />
-      <workItem from="1585041029099" duration="497000" />
-    </task>
-    <task id="LOCAL-00003" summary="add  q3/q8/q11">
-      <created>1580235186067</created>
-      <option name="number" value="00003" />
-      <option name="presentableId" value="LOCAL-00003" />
-      <option name="project" value="LOCAL" />
-      <updated>1580235186067</updated>
+      <workItem from="1585041029099" duration="1877000" />
     </task>
     <task id="LOCAL-00004" summary="add q6">
       <created>1580320003660</created>
@@ -633,7 +628,14 @@
       <option name="project" value="LOCAL" />
       <updated>1585027889055</updated>
     </task>
-    <option name="localTasksCounter" value="52" />
+    <task id="LOCAL-00052" summary="add q945">
+      <created>1585041706193</created>
+      <option name="number" value="00052" />
+      <option name="presentableId" value="LOCAL-00052" />
+      <option name="project" value="LOCAL" />
+      <updated>1585041706193</updated>
+    </task>
+    <option name="localTasksCounter" value="53" />
     <servers />
   </component>
   <component name="TypeScriptGeneratedFilesManager">
@@ -686,7 +688,6 @@
     </option>
   </component>
   <component name="VcsManagerConfiguration">
-    <MESSAGE value="add q94/98/144/145" />
     <MESSAGE value="update q98" />
     <MESSAGE value="add q110/q450/q701" />
     <MESSAGE value="add q1277" />
@@ -711,7 +712,8 @@
     <MESSAGE value="add q226" />
     <MESSAGE value="add q300" />
     <MESSAGE value="update Rocket.md" />
-    <option name="LAST_COMMIT_MESSAGE" value="update Rocket.md" />
+    <MESSAGE value="add q945" />
+    <option name="LAST_COMMIT_MESSAGE" value="add q945" />
   </component>
   <component name="WindowStateProjectService">
     <state x="320" y="115" key="#Inspections" timestamp="1581061018990">
@@ -726,10 +728,10 @@
       <screen x="0" y="0" width="1440" height="900" />
     </state>
     <state x="533" y="166" key="#com.intellij.ide.util.MemberChooser/0.0.1440.900@0.0.1440.900" timestamp="1578548165321" />
-    <state x="303" y="50" key="CommitChangelistDialog2" timestamp="1585027888852">
+    <state x="303" y="50" key="CommitChangelistDialog2" timestamp="1585108601733">
       <screen x="0" y="0" width="1440" height="900" />
     </state>
-    <state x="303" y="50" key="CommitChangelistDialog2/0.0.1440.900@0.0.1440.900" timestamp="1585027888852" />
+    <state x="303" y="50" key="CommitChangelistDialog2/0.0.1440.900@0.0.1440.900" timestamp="1585108601733" />
     <state x="143" y="78" width="1152" height="720" key="DiffContextDialog" timestamp="1585027870766">
       <screen x="0" y="0" width="1440" height="900" />
     </state>
@@ -784,10 +786,10 @@
       <screen x="0" y="0" width="1440" height="900" />
     </state>
     <state x="221" y="63" key="SettingsEditor/0.0.1440.900@0.0.1440.900" timestamp="1583244442349" />
-    <state x="320" y="190" key="Vcs.Push.Dialog.v2" timestamp="1585027890325">
+    <state x="320" y="190" key="Vcs.Push.Dialog.v2" timestamp="1585041707972">
       <screen x="0" y="0" width="1440" height="900" />
     </state>
-    <state x="320" y="190" key="Vcs.Push.Dialog.v2/0.0.1440.900@0.0.1440.900" timestamp="1585027890325" />
+    <state x="320" y="190" key="Vcs.Push.Dialog.v2/0.0.1440.900@0.0.1440.900" timestamp="1585041707972" />
     <state x="100" y="100" width="1240" height="700" key="com.intellij.history.integration.ui.views.DirectoryHistoryDialog" timestamp="1581744794182">
       <screen x="0" y="23" width="1440" height="797" />
     </state>
diff --git a/README.md b/README.md
index 7bbc887..79c53c7 100644
--- a/README.md
+++ b/README.md
@@ -69,6 +69,7 @@
 
 * [q21_合并两个有序链表](/src/递归/q21_合并两个有序链表)
 * [q101_对称二叉树](/src/递归/q101_对称二叉树)
+* [q104_二叉树的最大深度](/src/递归/q104_二叉树的最大深度)
 * [q226_翻转二叉树](/src/递归/q226_翻转二叉树)
 * [q236_二叉树的最近公共祖先](/src/递归/q236_二叉树的最近公共祖先)
 
@@ -81,6 +82,7 @@
 
 * [q5_最长回文子串](/src/动态规划/q5_最长回文子串)
 * [q53_最大子序和](/src/动态规划/q53_最大子序和)
+* [q70_爬楼梯](/src/动态规划/q70_爬楼梯)
 * [q118_杨辉三角](/src/动态规划/q118_杨辉三角)
 * [q300_最长上升子序列](/src/动态规划/q300_最长上升子序列)
 * [q746_使用最小花费爬楼梯](/src/动态规划/q746_使用最小花费爬楼梯)
diff --git a/src/动态规划/q70_爬楼梯/Solution.java b/src/动态规划/q70_爬楼梯/Solution.java
new file mode 100644
index 0000000..528397b
--- /dev/null
+++ b/src/动态规划/q70_爬楼梯/Solution.java
@@ -0,0 +1,20 @@
+package 动态规划.q70_爬楼梯;
+
+/**
+ * 动态规划 dp[i]表示到达第i阶的方法总数dp[i]=dp[i−1]+dp[i−2] o(n)
+ */
+public class Solution {
+
+    public int climbStairs(int n) {
+        if (n == 1) {
+            return 1;
+        }
+        int[] dp = new int[n + 1];
+        dp[1] = 1;
+        dp[2] = 2;
+        for (int i = 3; i <= n; i++) {
+            dp[i] = dp[i - 1] + dp[i - 2];
+        }
+        return dp[n];
+    }
+}
diff --git a/src/递归/q104_二叉树的最大深度/Solution.java b/src/递归/q104_二叉树的最大深度/Solution.java
new file mode 100644
index 0000000..ff9949e
--- /dev/null
+++ b/src/递归/q104_二叉树的最大深度/Solution.java
@@ -0,0 +1,17 @@
+package 递归.q104_二叉树的最大深度;
+
+/**
+ * 递归 o(n)
+ */
+public class Solution {
+
+    public int maxDepth(TreeNode root) {
+        if (root == null) {
+            return 0;
+        } else {
+            int leftHeight = maxDepth(root.left);
+            int rightHeight = maxDepth(root.right);
+            return Math.max(leftHeight, rightHeight) + 1;
+        }
+    }
+}
diff --git a/src/递归/q104_二叉树的最大深度/TreeNode.java b/src/递归/q104_二叉树的最大深度/TreeNode.java
new file mode 100644
index 0000000..ec216ba
--- /dev/null
+++ b/src/递归/q104_二叉树的最大深度/TreeNode.java
@@ -0,0 +1,11 @@
+package 递归.q104_二叉树的最大深度;
+
+public class TreeNode {
+    int val;
+    TreeNode left;
+    TreeNode right;
+
+    TreeNode(int x) {
+        val = x;
+    }
+}