subsets

Author: tech-cow

README.md

@@ -84,3 +84,9 @@ Success is like pregnancy, Everybody congratulates you but nobody knows how many
 |114|[Flatten Binary Tree to Linked List](https://leetcode.com/problems/flatten-binary-tree-to-linked-list/#/solutions)| [Python [Yu]](./tree/Yu/114.py) | _O(N)_| _O(1)_  | Medium | |[公瑾讲解](https://youtu.be/LfKRZ_qCmYQ)|
 |230|[Kth Smallest Element in a BST](https://leetcode.com/problems/kth-smallest-element-in-a-bst/#/description)| [Python [Yu]](./tree/Yu/230.py) | _O(N)_| _O(1)_  | Medium | |[公瑾讲解](https://youtu.be/CfNRc82ighw)|
 |582|[Kill Process](https://leetcode.com/problems/kill-process/#/description)| [Python [Yu]](./tree/Yu/582.py) | _O(N)_| _O(N)_  | Medium | |[公瑾讲解](https://youtu.be/fKR1n35Sj8s)|
+
+
+## Backtrack Medium
+|  #  | Title | Solution | Time | Space | Difficulty |Tag| Note|
+|-----|-------| -------- | ---- | ------|------------|---|-----|
+|78|[Subsets](https://leetcode.com/problems/subsets/#/description)| [Python [Yu]](./backtrack/Yu/78.py) | _O(N*(2^N))_| _O(2^N)_  | Medium | |[公瑾讲解](https://youtu.be/Az3PfUep7gk)|

backtrack/Yu/78.py

@@ -0,0 +1,33 @@
+# Yu Zhou
+# 78. Subsets
+# Given a set of distinct integers, nums, return all possible subsets.
+# Note: The solution set must not contain duplicate subsets.
+
+# If nums = [1,2,3], a solution is:
+
+# [
+#   [3],
+#   [1],
+#   [2],
+#   [1,2,3],
+#   [1,3],
+#   [2,3],
+#   [1,2],
+#   []
+# ]
+
+class Solution(object):
+    def subsets(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: List[List[int]]
+        """
+        self.res = []
+        def dfs(nums, temp, i):
+            self.res.append(temp[:])
+            for i in xrange(i, len(nums)):
+                temp.append(nums[i])
+                dfs(nums, temp, i + 1)
+                temp.pop()
+        dfs(nums, [], 0)
+        return self.res

tree/Yu/78.py

@@ -0,0 +1,33 @@
+# Yu Zhou
+# 78. Subsets
+# Given a set of distinct integers, nums, return all possible subsets.
+# Note: The solution set must not contain duplicate subsets.
+
+# If nums = [1,2,3], a solution is:
+
+# [
+#   [3],
+#   [1],
+#   [2],
+#   [1,2,3],
+#   [1,3],
+#   [2,3],
+#   [1,2],
+#   []
+# ]
+
+class Solution(object):
+    def subsets(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: List[List[int]]
+        """
+        self.res = []
+        def dfs(nums, temp, i):
+            self.res.append(temp[:])
+            for i in xrange(i, len(nums)):
+                temp.append(nums[i])
+                dfs(nums, temp, i + 1)
+                temp.pop()
+        dfs(nums, [], 0)
+        return self.res

tree/Yu/try.py

@@ -1,6 +1,6 @@
-def traversal(root):
-  if not root:
-    return None
-  print root.val
-  traversal(root.left)
-  traversal(root.right)
+arr1 = [3]
+arr2 = [5]
+res = arr1 + arr2
+arr2.pop()
+
+print res