Leetcode 78. Subsets

Author: kalpak92

Backtracking/Subsets.java

@@ -0,0 +1,59 @@
+import java.util.*;
+
+/**
+ * Given a set of distinct integers, nums, return all possible subsets (the power set).
+ * 
+ * Note: The solution set must not contain duplicate subsets.
+ * Example:
+ * Input: nums = [1,2,3]
+ * Output:
+ * [
+ *   [3],
+ *   [1],
+ *   [2],
+ *   [1,2,3],
+ *   [1,3],
+ *   [2,3],
+ *   [1,2],
+ *   []
+ * ]
+ */
+
+ public class Subsets 
+ {
+     public List<List<Integer>> findSubsets(int[] nums)
+     {
+         List<List<Integer>> result = new ArrayList<>();
+         Arrays.sort(nums);
+
+         backtrack(result, new ArrayList<>(), nums, 0);
+         return result;
+     }
+
+     private void backtrack(List<List<Integer>> result, List<Integer> temp, int[] nums, int start)
+     {
+         result.add(new ArrayList<>(temp));
+         System.out.println("start = " + start + " result currently -> " + result);
+
+         for(int i = start; i < nums.length; i++)
+         {
+            temp.add(nums[i]);
+            System.out.println("i = " + i + " temp currently -> " + temp);
+            System.out.println("Calling Backtrack recursive");
+            backtrack(result, temp, nums, i + 1);
+
+            System.out.println("After recursion call. i = " + i);
+            temp.remove(temp.size() - 1);
+            System.out.println("Temp currently after removal : " + temp);
+
+         }
+     }
+
+     public static void main(String[] args) {
+         Subsets obj = new Subsets();
+
+         int[] nums = {2, 1, 3};
+
+         System.out.println("Final result : " + obj.findSubsets(nums));
+     }
+ }

LeetCode/78. Subsets/Solution.java

@@ -0,0 +1,44 @@
+/**
+ * Given a set of distinct integers, nums, return all possible subsets (the power set).
+ * Note: The solution set must not contain duplicate subsets.
+ * 
+ * Example:
+ * Input: nums = [1,2,3]
+ * Output:
+ * [
+ *   [3],
+ *   [1],
+ *   [2],
+ *   [1,2,3],
+ *   [1,3],
+ *   [2,3],
+ *   [1,2],
+ *   []
+ * ]
+ */
+
+class Solution {
+    public List<List<Integer>> subsets(int[] nums) {
+        List<List<Integer>> result = new ArrayList<>();
+        
+        Arrays.sort(nums);
+        
+        backtrack(result, new ArrayList<>(), nums, 0);
+        
+        return result;
+    }
+    
+    private void backtrack(List<List<Integer>> result, List<Integer> temp, int[] nums, int start)
+    {
+        result.add(new ArrayList<>(temp));
+        
+        for(int i = start; i < nums.length; i++)
+        {
+            temp.add(nums[i]);
+            
+            backtrack(result, temp, nums, i+1);
+            
+            temp.remove(temp.size() - 1);
+        }
+    }
+}

LeetCode/README.md

@@ -24,6 +24,9 @@
 - [x] [Merge Intervals](https://github.com/kalpak92/DataStructures_Algorithms/tree/master/LeetCode/56.%20Merge%20Intervals)
 - [x] [Meeting Rooms II](https://github.com/kalpak92/DataStructures_Algorithms/tree/master/LeetCode/253.%20Meeting%20Rooms%20II)
 
+## Backtracking
+- [x] [Subsets]()
+
 ## Linked List
 
 - [x] [Add Two Numbers](https://github.com/kalpak92/DataStructures_Algorithms/tree/master/LeetCode/2.%20Add%20Two%20Numbers)