优化无法通过压力测试的习题

data/2.dailycode中阶/3.python/6.exercises/solution.md

@@ -24,7 +24,20 @@ if __name__ == "__main__":
 ## 答案
 
 ```python
-
+class Solution:
+    def subsets(self, nums):
+        allset = 2 ** len(nums)
+        result = []
+        for i in range(allset):
+            item = []
+            for j in range(len(nums)):
+                if i & (2 ** j):
+                    item.append(nums[j])
+            result.append(item)
+        return result
+if __name__ == "__main__":
+	s = Solution()
+	print (s.subsets([1,2,3]))
 ```
 
 ## 选项
@@ -32,17 +45,56 @@ if __name__ == "__main__":
 ### A
 
 ```python
-
+class Solution:
+    def subsets(self, nums):
+        allset = 2 ** len(nums)
+        result = []
+        for i in range(allset):
+            item = []
+            for j in range(len(nums)):
+                if 2 ** j:
+                    item.append(nums[j])
+            result.append(item)
+        return result
+if __name__ == "__main__":
+	s = Solution()
+	print (s.subsets([1,2,3]))
 ```
 
 ### B
 
 ```python
-
+class Solution:
+    def subsets(self, nums):
+        allset = 2 ** len(nums)
+        result = []
+        for i in range(allset):
+            item = []
+            for j in range(len(nums)):
+                if 2 * j:
+                    item.append(nums[j])
+            result.append(item)
+        return result
+if __name__ == "__main__":
+	s = Solution()
+	print (s.subsets([1,2,3]))
 ```
 
 ### C
 
 ```python
-
+class Solution:
+    def subsets(self, nums):
+        allset = 2 ** len(nums)
+        result = []
+        for i in range(allset):
+            item = []
+            for j in range(len(nums)):
+                if i & (2 * j):
+                    item.append(nums[j])
+            result.append(item)
+        return result
+if __name__ == "__main__":
+	s = Solution()
+	print (s.subsets([1,2,3]))
 ```
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