Merge pull request #314 from tharun694/question

subset question and approach added in backtracking directory.

Author: abhishektripathi66

.idea/misc.xml

@@ -0,0 +1,30 @@
+
+class Subset{
+    public static void main(String[]args){
+        int[]nums={1,2,3};
+        System.out.println(subsets(nums));
+    }
+  static public List<List<Integer>> subsets(int[] nums) {
+         Arrays.sort(nums);
+        List<List<Integer>> outer=new ArrayList<>();
+        List<Integer> internal=new ArrayList<>();
+
+        int end=0;
+        outer.add(internal);
+        for(int i=0;i<nums.length;i++){
+                    int start=0;
+if(i>0&&nums[i-1]==nums[i]){
+  start=end+1;  
+}
+end=outer.size()-1;
+int n=outer.size();
+for(int j=start;j<n;j++){
+    internal=new ArrayList<>(outer.get(j));
+    internal.add(nums[i]);
+    outer.add(internal);
+}
+
+        }
+        return outer;
+    }
+}

src/algorithms/backtracking/Subset.java

@@ -0,0 +1,20 @@
+
+# Subsets (Unique Subsets)
+
+## 💡 Idea
+Generate all unique subsets from an array that may contain duplicates using an **iterative approach**.
+
+## ⚙️ Approach
+1. Sort the array to handle duplicates easily.  
+2. For each number:
+   - Copy all existing subsets.
+   - Add the current number to each copy.
+   - If it's a duplicate, start from the last new subsets only.
+
+## ⏱️ Complexity
+- **Time:** O(N × 2^N)  
+- **Space:** O(N × 2^N)
+
+## 🧩 Example
+Input: `[1,2,2]`  
+Output: `[[], [1], [2], [1,2], [2,2], [1,2,2]]`;