Complete Backtracking-2

Problem72.java

@@ -0,0 +1,26 @@
+// Time Complexity : O(n × 2ⁿ) - 2ⁿ
+// Space Complexity : O(n)
+
+class Solution {
+    List<List<Integer>> result;
+    public List<List<Integer>> subsets(int[] nums) {
+        this.result = new ArrayList<>();
+        List<Integer> path = new ArrayList<>();
+        helper(nums, 0, path);
+        return result;
+    }
+
+    private void helper(int[] nums, int i, List<Integer> path) {
+
+        if (i == nums.length) {
+            result.add(new ArrayList<>(path)); 
+            return;
+        }
+
+        helper(nums, i + 1, path);
+
+        path.add(nums[i]);              
+        helper(nums, i + 1, path);      
+        path.remove(path.size() - 1);
+    }
+}

Problem73.java

@@ -0,0 +1,40 @@
+// Time Complexity : O(2^n * n) 
+// Space Complexity : O(n^2) 
+
+class Solution {
+    public List<List<String>> partition(String s) {
+        List<List<String>> result = new ArrayList<>();
+        helper(s, 0, new ArrayList<>(), result);
+        return result;
+    }
+
+    private void helper(String s, int pivot, List<String> path, List<List<String>> result) {
+        //base
+        if(pivot == s.length()) {
+            result.add(new ArrayList<>(path));
+            return;
+        }
+
+        //logic
+        for(int i = pivot; i < s.length(); i++) {
+            String subStr = s.substring(pivot, i+1);
+            if(isPalindrome(subStr)){
+                path.add(subStr);
+                helper(s, i+1, path, result);
+                path.remove(path.size()-1);
+            }
+        }
+    }
+
+    private boolean isPalindrome(String s) {
+        int left = 0; int right = s.length()-1;
+        while(left < right) {
+            if(s.charAt(left) != s.charAt(right)) {
+                return false;
+            }
+            left++; right--;
+        }
+
+        return true;
+    }
+}