Solved

Problem1.java

@@ -0,0 +1,23 @@
+class Solution {
+    List<List<Integer>> result;
+    public List<List<Integer>> subsets(int[] nums) {
+        result = new ArrayList<>();
+        if (nums == null|| nums.length == 0) return result;
+
+        backtrack(nums, new ArrayList<>(), 0);
+
+        return result;
+    }
+
+    public void backtrack(int[] nums, List<Integer> set, int idx) {
+        result.add(new ArrayList<>(set));
+
+        for (int i=idx; i<nums.length; i++) {
+            if (!set.contains(nums[i])) {
+                set.add(nums[i]);
+                backtrack(nums, set, i + 1);
+                set.remove(set.size() - 1);
+            }
+        }
+    }
+}

problem2.java

@@ -0,0 +1,43 @@
+class Solution {
+    List<List<String>> result;
+    public List<List<String>> partition(String s) {
+        if (s == null || s.length() == 0) return new ArrayList<>();
+
+        result = new ArrayList<>();
+        List<String> currList = new ArrayList<>();
+        backtrack(s, 0, currList);
+
+        return result;
+    }
+
+    private void backtrack(String s, int idx, List<String> currList) {
+
+        if (idx == s.length()) {
+            result.add(new ArrayList<>(currList));
+            return;
+        }
+
+        for (int j = 1; j <= s.length() - idx; j++) {
+
+            if (isPalindrome(s.substring(idx, idx+j))) {
+
+                currList.add(s.substring(idx, idx+j));
+                backtrack(s, idx+j, currList);
+                currList.remove(currList.size() - 1);
+
+            }
+
+        }
+
+    }
+
+    private boolean isPalindrome(String s) {
+
+        int l = s.length();
+        for (int i=0; i<l/2; i++) {
+            if (s.charAt(i) != s.charAt(l - i - 1)) return false;
+        }
+        return true;
+
+    }
+}