diff --git a/.idea/workspace.xml b/.idea/workspace.xml
index df9bbec..f573a25 100644
--- a/.idea/workspace.xml
+++ b/.idea/workspace.xml
@@ -2,8 +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/q78_子集/Solution.java" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/Rocket.md" beforeDir="false" afterPath="$PROJECT_DIR$/Rocket.md" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/README.md" beforeDir="false" afterPath="$PROJECT_DIR$/README.md" afterDir="false" />
     </list>
     <option name="SHOW_DIALOG" value="false" />
     <option name="HIGHLIGHT_CONFLICTS" value="true" />
@@ -80,7 +81,14 @@
       <recent name="$PROJECT_DIR$/src/q206/f1" />
     </key>
   </component>
-  <component name="RunManager" selected="Application.Solution (3)">
+  <component name="RunManager" selected="Application.Solution">
+    <configuration name="Main" type="Application" factoryName="Application" temporary="true" nameIsGenerated="true">
+      <option name="MAIN_CLASS_NAME" value="Main" />
+      <module name="LeetCode" />
+      <method v="2">
+        <option name="Make" enabled="true" />
+      </method>
+    </configuration>
     <configuration name="Solution (1)" type="Application" factoryName="Application" temporary="true" nameIsGenerated="true">
       <option name="MAIN_CLASS_NAME" value="contest.test.Solution" />
       <module name="LeetCode" />
@@ -95,11 +103,11 @@
       </method>
     </configuration>
     <configuration name="Solution (2)" type="Application" factoryName="Application" temporary="true" nameIsGenerated="true">
-      <option name="MAIN_CLASS_NAME" value="contest.q1.Solution" />
+      <option name="MAIN_CLASS_NAME" value="动态规划.q70_爬楼梯.Solution" />
       <module name="LeetCode" />
       <extension name="coverage">
         <pattern>
-          <option name="PATTERN" value="contest.q1.*" />
+          <option name="PATTERN" value="动态规划.q70_爬楼梯.*" />
           <option name="ENABLED" value="true" />
         </pattern>
       </extension>
@@ -120,25 +128,12 @@
         <option name="Make" enabled="true" />
       </method>
     </configuration>
-    <configuration name="Solution (4)" type="Application" factoryName="Application" temporary="true" nameIsGenerated="true">
-      <option name="MAIN_CLASS_NAME" value="contest.Solution" />
-      <module name="LeetCode" />
-      <extension name="coverage">
-        <pattern>
-          <option name="PATTERN" value="contest.*" />
-          <option name="ENABLED" value="true" />
-        </pattern>
-      </extension>
-      <method v="2">
-        <option name="Make" enabled="true" />
-      </method>
-    </configuration>
     <configuration name="Solution" type="Application" factoryName="Application" temporary="true" nameIsGenerated="true">
-      <option name="MAIN_CLASS_NAME" value="contest.q2.Solution" />
+      <option name="MAIN_CLASS_NAME" value="数组操作.q78_子集.Solution" />
       <module name="LeetCode" />
       <extension name="coverage">
         <pattern>
-          <option name="PATTERN" value="contest.q2.*" />
+          <option name="PATTERN" value="数组操作.q78_子集.*" />
           <option name="ENABLED" value="true" />
         </pattern>
       </extension>
@@ -187,11 +182,11 @@
     </configuration>
     <recent_temporary>
       <list>
-        <item itemvalue="Application.Solution (3)" />
-        <item itemvalue="Application.Solution (1)" />
-        <item itemvalue="Application.Solution (4)" />
         <item itemvalue="Application.Solution" />
         <item itemvalue="Application.Solution (2)" />
+        <item itemvalue="Application.Main" />
+        <item itemvalue="Application.Solution (3)" />
+        <item itemvalue="Application.Solution (1)" />
       </list>
     </recent_temporary>
   </component>
@@ -263,14 +258,11 @@
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       <workItem from="1589857792404" duration="221000" />
       <workItem from="1591254276718" duration="1779000" />
-      <workItem from="1591328701703" duration="290000" />
-    </task>
-    <task id="LOCAL-00019" summary="update q10">
-      <created>1581705262462</created>
-      <option name="number" value="00019" />
-      <option name="presentableId" value="LOCAL-00019" />
-      <option name="project" value="LOCAL" />
-      <updated>1581705262462</updated>
+      <workItem from="1591328701703" duration="12445000" />
+      <workItem from="1591365073366" duration="5000" />
+      <workItem from="1591451838662" duration="723000" />
+      <workItem from="1591524368167" duration="184000" />
+      <workItem from="1591587079718" duration="2273000" />
     </task>
     <task id="LOCAL-00020" summary="update q206">
       <created>1581705659513</created>
@@ -608,7 +600,14 @@
       <option name="project" value="LOCAL" />
       <updated>1591266199793</updated>
     </task>
-    <option name="localTasksCounter" value="68" />
+    <task id="LOCAL-00068" summary="update">
+      <created>1591337784803</created>
+      <option name="number" value="00068" />
+      <option name="presentableId" value="LOCAL-00068" />
+      <option name="project" value="LOCAL" />
+      <updated>1591337784803</updated>
+    </task>
+    <option name="localTasksCounter" value="69" />
     <servers />
   </component>
   <component name="TypeScriptGeneratedFilesManager">
@@ -693,54 +692,69 @@
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+    <state x="404" y="60" key="CommitChangelistDialog2" timestamp="1591337784627">
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+      <screen x="0" y="23" width="1920" height="977" />
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     <state width="1398" height="204" key="GridCell.Tab.1.right/0.0.1440.900@0.0.1440.900" timestamp="1587225087589" />
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@@ -749,11 +763,11 @@
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diff --git a/README.md b/README.md
index cbc5038..6cea521 100644
--- a/README.md
+++ b/README.md
@@ -54,6 +54,7 @@
 
 * [q54_螺旋矩阵](/src/数组操作/q54_螺旋矩阵)
 * [q73_矩阵置零](/src/数组操作/q73_矩阵置零)
+* [q78_子集](/src/数组操作/q78_子集)
 * [q945_使数组唯一的最小增量](/src/数组操作/q945_使数组唯一的最小增量)
 
 ### 栈相关
diff --git a/src/数组操作/q78_子集/Solution.java b/src/数组操作/q78_子集/Solution.java
new file mode 100644
index 0000000..d47219e
--- /dev/null
+++ b/src/数组操作/q78_子集/Solution.java
@@ -0,0 +1,24 @@
+package 数组操作.q78_子集;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * 向子集中添加子集合 o(n*2^n)
+ */
+public class Solution {
+
+    public List<List<Integer>> subsets(int[] nums) {
+        List<List<Integer>> result = new ArrayList<>();
+        result.add(new ArrayList<>());
+        for (int i = 0; i < nums.length; i++) {
+            int size = result.size();
+            for (int j = 0; j < size; j++) {
+                List<Integer> temp = new ArrayList<>(result.get(j));
+                temp.add(nums[i]);
+                result.add(temp);
+            }
+        }
+        return result;
+    }
+}