Create 78-Subsets.java

Author: SharmaTushar1

java/78-Subsets.java

@@ -0,0 +1,23 @@
+//The idea is to have two conditions: One in which we will take the element into consideration, Second in which we won't take the element into consideration.
+//This video was good for code explanation. https://www.youtube.com/watch?v=6BPurabdAl4&t=508s&ab_channel=Fraz
+class Solution {
+    public List<List<Integer>> subsets(int[] nums) {
+        List<List<Integer>> ans = new ArrayList<>();
+        List<Integer> list = new ArrayList<>();
+        helper(ans, 0, nums, list);
+        return ans;
+    }
+    
+    public void helper(List<List<Integer>> ans, int start, int[] nums, List<Integer> list) {
+        if (start>=nums.length) {
+            ans.add(new ArrayList<>(list)); //In java, we will have to add like this otherwise it'll give null as it'll just have the reference instead of actual values.
+        } else {
+            //add the element and start the  recursive call
+            list.add(nums[start]);
+            helper(ans, start+1, nums, list);
+            //remove the element and do the backtracking call.
+            list.remove(list.size()-1);
+            helper(ans, start+1, nums, list);
+        }
+    }
+}