Generate subsets for a set, without duplication

Recursion/GenerateSubsets.java

@@ -0,0 +1,59 @@
+import java.util.ArrayList;
+import java.util.List;
+
+public class GenerateSubsets {
+    /**
+     * time complexity is 2^n * n/2
+     * space complexity n + n + is 2^n * n/2
+     */
+
+    static List<List<Integer>> result1 = new ArrayList<>();
+    static List<String> result2 = new ArrayList<>();
+
+    private static void generateSubsetsHelper1(int[] arr, int idx, List<Integer> slate) {
+
+        if (idx == arr.length) {
+            result1.add(new ArrayList<>(slate));
+            return;
+        }
+        generateSubsetsHelper1(arr, idx + 1, slate);
+        slate.add(arr[idx]);
+        generateSubsetsHelper1(arr, idx + 1, slate);
+        slate.remove(slate.size()-1);
+    }
+
+
+    private static void generateSubsetsHelper2(String s, int idx, char[] slate,int curSl) {
+        if (idx == s.length()) {
+            result2.add(new String(slate, 0,curSl));
+            return;
+        }
+        generateSubsetsHelper2(s, idx + 1, slate, curSl);
+        slate[curSl] = s.charAt(idx);
+        generateSubsetsHelper2(s, idx + 1, slate, curSl + 1);
+    }
+
+    public static void generateSubsets1(int[] arr) {
+        List<Integer> slate = new ArrayList<>();
+        generateSubsetsHelper1(arr, 0, slate);
+    }
+
+    public static void generateSubsets2(String s) {
+        char[] slate = new char[s.length()];
+        generateSubsetsHelper2(s, 0, slate, 0);
+
+    }
+
+
+    public static void main(String[] args) {
+        int[] arr = {1,2,3};
+        String s = "123";
+        generateSubsets1(arr);
+        //generateSubsets2(s);
+        //System.out.println(result2);
+        System.out.println(result1);
+    }
+}
+
+
+