[Partition and Subsets dfs with loop]

Parttion.java

@@ -0,0 +1,42 @@
+// Time Complexity: O(n * 2^n)
+// Space Complexity: O(n)
+// Ran on Leetcode succefully: yes
+class Solution {
+    List<List<String>> ans;
+    public List<List<String>> partition(String s) {
+        ans = new ArrayList<>();
+        // start from pivot = 0
+        helperPartition(s, 0, new ArrayList<>());
+        return ans;
+    }
+
+    public void helperPartition(String s, int pivot, List<String> curr) {
+        // if pivot manages to reach the end then the curr is valid
+        if (pivot == s.length()) {
+            ans.add(new ArrayList<>(curr));
+            return;
+        }
+
+        for ( int i = pivot; i < s.length(); i++) {
+            // before adding substring check if it is palindrome;
+            if(isPalindrome(s.substring(pivot, i + 1))) {
+                curr.add(s.substring(pivot, i + 1));
+                helperPartition(s, i + 1, curr);
+                curr.remove(curr.size() - 1);
+            }
+        }
+    }
+    // Check if a string is palindrome
+    public boolean isPalindrome(String s) {
+        int L = 0;
+        int R = s.length() - 1;
+        // if left and right meet without violating the condition then its a palindrome
+        while (L < R) {
+            if(s.charAt(L++) != s.charAt(R--)) {
+                return false;
+            }
+        }
+        return true;
+
+    }
+}

Subsets.java

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+// Time Complexity: O(n * 2^n)
+// Space Complexity: O(n)
+// Ran on Leetcode succefully: yes
+class Solution {
+    List<List<Integer>> ans;
+    public List<List<Integer>> subsets(int[] nums) {
+        ans = new ArrayList<>();
+        helperSubsets(nums, 0, new ArrayList<>());
+        return ans;
+    }
+
+    public void helperSubsets(int [] nums, int pivot, List<Integer> list) {
+        // add deep copy to ans
+        ans.add(new ArrayList(list));
+        for(int i = pivot; i < nums.length; i++) {
+            list.add(nums[i]);
+            // explore subsets
+            helperSubsets(nums, i + 1, list);
+            // backtrack
+            list.remove(list.size() - 1);
+        }
+    }
+}