Create SubsetsII.java

Author: 17tanya

Backtracking/SubsetsII.java

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+//LeetCode 90. Subsets II
+//Question - https://leetcode.com/problems/subsets-ii/
+
+class Solution {
+    public List<List<Integer>> subsetsWithDup(int[] nums) {
+        List<List<Integer>> res = new ArrayList<>();
+        
+        //By sorting the array duplicates would come together consecutively
+        Arrays.sort(nums);
+        
+        helper(nums, 0, new ArrayList<>(), res);
+        return res;
+    }
+    
+    public void helper(int nums[], int index, List<Integer> subset, List<List<Integer>> res){
+        res.add(new ArrayList<>(subset));
+        
+        for(int i = index ; i < nums.length ; i++){
+            //Always include the first distinct number and ignore the following duplicates
+            if(i > index && nums[i] == nums[i-1]) continue;
+            
+            subset.add(nums[i]);
+            helper(nums, i+1, subset, res);
+            subset.remove(subset.size()-1);
+            
+        }
+    }
+}