Add Subsets using Bit Manipulation

Author: Hardvan

src/cpp/SubsetsBitManipulation.cpp

@@ -0,0 +1,62 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+/*
+Problem Statement:
+Given an integer array nums of unique elements, return all possible
+subsets (the power set).
+
+The solution set must not contain duplicate subsets. Return the solution in any order.
+*/
+
+// Using Bit Manipulation
+// 1) Traverse all subsets
+// 2) Traverse all elements of nums
+// 3) Check if jth bit is set in i
+// It is like for 3 elements:
+// 000, 001, 010, 011, 100, 101, 110, 111
+// where 1 means that element is present in the subset
+// Time: O(n * 2ⁿ)
+// Space: O(1)
+vector<vector<int>> subsets(vector<int> &nums)
+{
+    int n = nums.size();
+    int total = 1 << n; // 2ⁿ
+    vector<vector<int>> ans(total);
+
+    // Traverse all subsets
+    for (int i = 0; i < total; i++) // 2ⁿ
+    {
+        // Traverse elements of nums
+        for (int j = 0; j < n; j++) // n
+        {
+            // Check if jth bit is set in i
+            if ((1 << j) & i)
+            {
+                ans[i].push_back(nums[j]);
+            }
+        }
+    }
+
+    return ans;
+}
+
+int main()
+{
+    vector<int> nums = {1, 2, 3};
+    vector<vector<int>> ans = subsets(nums);
+
+    cout << "Subsets are: \n";
+    for (auto v : ans)
+    {
+        cout << "[ ";
+        for (auto i : v)
+        {
+            cout << i << " ";
+        }
+        cout << "]\n";
+    }
+
+    return 0;
+}