Print all Subsets in Java

Leetcode-solutions/Subsets.java

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+// Given an integer array nums of unique elements, return all possible subsets.
+// Problem link: https://leetcode.com/problems/subsets/
+
+class Solution {
+
+    private List< List<Integer> > allSubset = new ArrayList< List<Integer> >();
+    private List< Integer > bag = new ArrayList<Integer>();
+
+    private void makeSubset(int startIndex, int[] nums){
+
+        // Add current subset into final result
+        // Java object is passing by refernce, so we have to make a copy here
+        allSubset.add(new ArrayList<Integer>(bag));
+
+
+        // Base cases aka stop condition:
+        // No more element
+        if( startIndex == nums.length ){
+            return;
+        }
+
+        //// General cases
+        // Current level, we choouse element on index i
+        for( int i = startIndex ; i < nums.length ; i++ ){ 
+
+            bag.add( nums[i] );            // put this element into bag
+            makeSubset(i+1, nums );   // make subset from remaining elements
+            bag.remove(bag.size()-1);     // undo selection
+        }
+        return;
+
+    }
+    public List<List<Integer>> subsets(int[] nums) {
+
+         makeSubset(0, nums);    
+         return allSubset;
+    }
+}