diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index 3ab00d5..47ff3f7 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -1,12 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="ChangeListManager">
-    <list default="true" id="af7ffdf2-4ddc-4ed6-8222-60ed5acbc2ed" name="Default Changelist" comment="">
-      <change afterPath="$PROJECT_DIR$/src/区间合并/q56_合并区间/Solution.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" />
-      <change beforePath="$PROJECT_DIR$/Rocket.md" beforeDir="false" afterPath="$PROJECT_DIR$/Rocket.md" afterDir="false" />
-    </list>
+    <list default="true" id="af7ffdf2-4ddc-4ed6-8222-60ed5acbc2ed" name="Default Changelist" comment="" />
     <option name="SHOW_DIALOG" value="false" />
     <option name="HIGHLIGHT_CONFLICTS" value="true" />
     <option name="HIGHLIGHT_NON_ACTIVE_CHANGELIST" value="false" />
@@ -58,13 +53,13 @@
     <property name="WebServerToolWindowFactoryState" value="false" />
     <property name="add_unversioned_files" value="true" />
     <property name="aspect.path.notification.shown" value="true" />
-    <property name="last_opened_file_path" value="$PROJECT_DIR$/src/hash相关" />
+    <property name="last_opened_file_path" value="$PROJECT_DIR$" />
     <property name="nodejs_interpreter_path.stuck_in_default_project" value="undefined stuck path" />
     <property name="nodejs_npm_path_reset_for_default_project" value="true" />
-    <property name="project.structure.last.edited" value="Modules" />
+    <property name="project.structure.last.edited" value="Problems" />
     <property name="project.structure.proportion" value="0.15" />
     <property name="project.structure.side.proportion" value="0.2" />
-    <property name="settings.editor.selected.configurable" value="MavenSettings" />
+    <property name="settings.editor.selected.configurable" value="preferences.lookFeel" />
   </component>
   <component name="RecentsManager">
     <key name="CopyClassDialog.RECENTS_KEY">
@@ -81,7 +76,7 @@
       <recent name="$PROJECT_DIR$/src/q206/f1" />
     </key>
   </component>
-  <component name="RunManager" selected="Application.Solution (4)">
+  <component name="RunManager" selected="Application.Solution (5)">
     <configuration name="Solution (1)" type="Application" factoryName="Application" temporary="true" nameIsGenerated="true">
       <option name="MAIN_CLASS_NAME" value="hash相关.q1_两数之和.f1.Solution" />
       <module name="LeetCode" />
@@ -134,12 +129,12 @@
         <option name="Make" enabled="true" />
       </method>
     </configuration>
-    <configuration name="Solution" type="Application" factoryName="Application" temporary="true" nameIsGenerated="true">
-      <option name="MAIN_CLASS_NAME" value="回溯法.q22_括号生成.f2.Solution" />
+    <configuration name="Solution (5)" type="Application" factoryName="Application" temporary="true" nameIsGenerated="true">
+      <option name="MAIN_CLASS_NAME" value="递归.q101_对称二叉树.f2.Solution" />
       <module name="LeetCode" />
       <extension name="coverage">
         <pattern>
-          <option name="PATTERN" value="回溯法.q22_括号生成.f2.*" />
+          <option name="PATTERN" value="递归.q101_对称二叉树.f2.*" />
           <option name="ENABLED" value="true" />
         </pattern>
       </extension>
@@ -227,11 +222,11 @@
     </configuration>
     <recent_temporary>
       <list>
+        <item itemvalue="Application.Solution (5)" />
         <item itemvalue="Application.Solution (4)" />
         <item itemvalue="Application.Solution (3)" />
         <item itemvalue="Application.Solution (2)" />
         <item itemvalue="Application.Solution (1)" />
-        <item itemvalue="Application.Solution (2)" />
       </list>
     </recent_temporary>
   </component>
@@ -280,6 +275,7 @@
       <workItem from="1582552791282" duration="3963000" />
       <workItem from="1582634245000" duration="13006000" />
       <workItem from="1582873496305" duration="7292000" />
+      <workItem from="1582970835768" duration="70000" />
     </task>
     <task id="LOCAL-00001" summary="add q5/q7/q172">
       <created>1580045439607</created>
@@ -678,25 +674,25 @@
     <state x="144" y="78" width="1152" height="720" key="DiffContextDialog/0.0.1440.900@0.0.1440.900" timestamp="1582900981690" />
     <state x="144" y="78" width="1152" height="720" key="DiffContextDialog/0.23.1440.793@0.23.1440.793" timestamp="1582714686712" />
     <state x="144" y="78" width="1152" height="720" key="DiffContextDialog/0.23.1440.797@0.23.1440.797" timestamp="1581927787180" />
-    <state width="1398" height="236" key="GridCell.Tab.0.bottom" timestamp="1582724240264">
+    <state width="1398" height="245" key="GridCell.Tab.0.bottom" timestamp="1582970995234">
       <screen x="0" y="0" width="1440" height="900" />
     </state>
-    <state width="1398" height="236" key="GridCell.Tab.0.bottom/0.0.1440.900@0.0.1440.900" timestamp="1582724240264" />
+    <state width="1398" height="245" key="GridCell.Tab.0.bottom/0.0.1440.900@0.0.1440.900" timestamp="1582970995234" />
     <state width="1398" height="177" key="GridCell.Tab.0.bottom/0.23.1440.797@0.23.1440.797" timestamp="1581533895880" />
-    <state width="1398" height="236" key="GridCell.Tab.0.center" timestamp="1582724240261">
+    <state width="1398" height="245" key="GridCell.Tab.0.center" timestamp="1582970995233">
       <screen x="0" y="0" width="1440" height="900" />
     </state>
-    <state width="1398" height="236" key="GridCell.Tab.0.center/0.0.1440.900@0.0.1440.900" timestamp="1582724240261" />
+    <state width="1398" height="245" key="GridCell.Tab.0.center/0.0.1440.900@0.0.1440.900" timestamp="1582970995233" />
     <state width="1398" height="177" key="GridCell.Tab.0.center/0.23.1440.797@0.23.1440.797" timestamp="1581533895878" />
-    <state width="1398" height="236" key="GridCell.Tab.0.left" timestamp="1582724240261">
+    <state width="1398" height="245" key="GridCell.Tab.0.left" timestamp="1582970995232">
       <screen x="0" y="0" width="1440" height="900" />
     </state>
-    <state width="1398" height="236" key="GridCell.Tab.0.left/0.0.1440.900@0.0.1440.900" timestamp="1582724240261" />
+    <state width="1398" height="245" key="GridCell.Tab.0.left/0.0.1440.900@0.0.1440.900" timestamp="1582970995232" />
     <state width="1398" height="177" key="GridCell.Tab.0.left/0.23.1440.797@0.23.1440.797" timestamp="1581533895878" />
-    <state width="1398" height="236" key="GridCell.Tab.0.right" timestamp="1582724240263">
+    <state width="1398" height="245" key="GridCell.Tab.0.right" timestamp="1582970995234">
       <screen x="0" y="0" width="1440" height="900" />
     </state>
-    <state width="1398" height="236" key="GridCell.Tab.0.right/0.0.1440.900@0.0.1440.900" timestamp="1582724240263" />
+    <state width="1398" height="245" key="GridCell.Tab.0.right/0.0.1440.900@0.0.1440.900" timestamp="1582970995234" />
     <state width="1398" height="177" key="GridCell.Tab.0.right/0.23.1440.797@0.23.1440.797" timestamp="1581533895879" />
     <state width="1398" height="204" key="GridCell.Tab.1.bottom" timestamp="1581745235895">
       <screen x="0" y="0" width="1440" height="900" />
@@ -718,10 +714,10 @@
     </state>
     <state width="1398" height="204" key="GridCell.Tab.1.right/0.0.1440.900@0.0.1440.900" timestamp="1581745235894" />
     <state width="1398" height="304" key="GridCell.Tab.1.right/0.23.1440.797@0.23.1440.797" timestamp="1580408030266" />
-    <state x="221" y="63" key="SettingsEditor" timestamp="1582961080628">
+    <state x="221" y="63" key="SettingsEditor" timestamp="1582970905626">
       <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="1582961080628" />
+    <state x="221" y="63" key="SettingsEditor/0.0.1440.900@0.0.1440.900" timestamp="1582970905626" />
     <state x="320" y="190" key="Vcs.Push.Dialog.v2" timestamp="1582901004760">
       <screen x="0" y="0" width="1440" height="900" />
     </state>
@@ -730,6 +726,10 @@
       <screen x="0" y="23" width="1440" height="797" />
     </state>
     <state x="100" y="100" width="1240" height="700" key="com.intellij.history.integration.ui.views.DirectoryHistoryDialog/0.23.1440.797@0.23.1440.797" timestamp="1581744794182" />
+    <state x="397" y="282" key="com.intellij.ide.util.TipDialog" timestamp="1582970837451">
+      <screen x="0" y="0" width="1440" height="900" />
+    </state>
+    <state x="397" y="282" key="com.intellij.ide.util.TipDialog/0.0.1440.900@0.0.1440.900" timestamp="1582970837451" />
     <state x="378" y="207" width="683" height="486" key="find.popup" timestamp="1582564254151">
       <screen x="0" y="0" width="1440" height="900" />
     </state>