update readme

Author: hogan-tech

0078-subsets/0078-subsets.py

@@ -1,9 +1,54 @@
 # time complexity: O(n*2^n)
-# space complexity: O(n*2^n)
+# space complexity: O(n)
 from itertools import chain, combinations
 from typing import List
 
 
+class Solution:
+    def subsets(self, nums: List[int]) -> List[List[int]]:
+        result = []
+
+        def backtrack(start: int, comb: List[int]):
+            result.append(list(comb))
+            for i in range(start, len(nums)):
+                comb.append(nums[i])
+                backtrack(i + 1, comb)
+                comb.pop()
+
+        backtrack(0, [])
+        return result
+
+# time complexity: O(n*2^n)
+# space complexity: O(n*2^n)
+class Solution:
+    def subsets(self, nums):
+        result = [[]]
+        for num in nums:
+            newSubsets = []
+            for curr in result:
+                temp = curr.copy()
+                temp.append(num)
+                newSubsets.append(temp)
+            for curr in newSubsets:
+                result.append(curr)
+        return result
+
+# time complexity: O(n*2^n)
+# space complexity: O(n)
+class Solution:
+    def subsets(self, nums: List[int]) -> List[List[int]]:
+        n = len(nums)
+        result = []
+
+        for i in range(2**n, 2 ** (n + 1)):
+            # generate bitmask, from 0..00 to 1..11
+            bitmask = bin(i)[3:]
+            # append subset corresponding to that bitmask
+            result.append([nums[j] for j in range(n) if bitmask[j] == "1"])
+
+        return result
+
+
 class Solution:
     def subsets(self, nums: List[int]) -> List[List[int]]:
         result = list(chain.from_iterable(combinations(nums, r)
@@ -12,16 +57,16 @@ def subsets(self, nums: List[int]) -> List[List[int]]:
             result[i] = list(item)
         return result
 
-# class Solution:
-#    def subsets(self, nums: List[int]) -> List[List[int]]:
-#        output = [[]]
-
-#        for num in nums:
-#            output += [curr + [num] for curr in output]
 
-#        return output
+class Solution:
+    def subsets(self, nums: List[int]) -> List[List[int]]:
+        output = [[]]
+        for num in nums:
+            output += [curr + [num] for curr in output]
+        return output
 
 
 nums = [1, 2, 3]
-
+print(Solution().subsets(nums))
+nums = [0]
 print(Solution().subsets(nums))

0078-subsets/README.md

@@ -115,19 +115,3 @@ It helps others discover the repo and keeps the project growing.
 ---
 
 Feedback / Questions → open an Issue or reach out on [LinkedIn](https://www.linkedin.com/in/hogan-l/)  
-
-<!---LeetCode Topics Start-->
-# LeetCode Topics
-## Array
-|  |
-| ------- |
-| [0078-subsets](https://github.com/hogan-tech/leetcode-solution/tree/master/0078-subsets) |
-## Backtracking
-|  |
-| ------- |
-| [0078-subsets](https://github.com/hogan-tech/leetcode-solution/tree/master/0078-subsets) |
-## Bit Manipulation
-|  |
-| ------- |
-| [0078-subsets](https://github.com/hogan-tech/leetcode-solution/tree/master/0078-subsets) |
-<!---LeetCode Topics End-->

Python/0078-subsets.py

@@ -1,17 +1,19 @@
-<h2><a href="https://leetcode.com/problems/subsets/">78. Subsets</a></h2><h3>Medium</h3><hr><div><p>Given an integer array <code>nums</code> of <strong>unique</strong> elements, return <em>all possible</em> <span data-keyword="subset"><em>subsets</em></span> <em>(the power set)</em>.</p>
+<h2><a href="https://leetcode.com/problems/subsets">78. Subsets</a></h2><h3>Medium</h3><hr><p>Given an integer array <code>nums</code> of <strong>unique</strong> elements, return <em>all possible</em> <span data-keyword="subset"><em>subsets</em></span> <em>(the power set)</em>.</p>
 
 <p>The solution set <strong>must not</strong> contain duplicate subsets. Return the solution in <strong>any order</strong>.</p>
 
 <p>&nbsp;</p>
 <p><strong class="example">Example 1:</strong></p>
 
-<pre><strong>Input:</strong> nums = [1,2,3]
+<pre>
+<strong>Input:</strong> nums = [1,2,3]
 <strong>Output:</strong> [[],[1],[2],[1,2],[3],[1,3],[2,3],[1,2,3]]
 </pre>
 
 <p><strong class="example">Example 2:</strong></p>
 
-<pre><strong>Input:</strong> nums = [0]
+<pre>
+<strong>Input:</strong> nums = [0]
 <strong>Output:</strong> [[],[0]]
 </pre>
 
@@ -23,4 +25,3 @@
 	<li><code>-10 &lt;= nums[i] &lt;= 10</code></li>
 	<li>All the numbers of&nbsp;<code>nums</code> are <strong>unique</strong>.</li>
 </ul>
-</div>