Complete Trees-3

Problem47.java

@@ -0,0 +1,33 @@
+// Time Complexity : O(N)
+// Space Complexity : O(h)
+// Did this code successfully run on Leetcode : Yes
+// Any problem you faced while coding this : No
+
+class Solution {
+    private List<List<Integer>> result;
+    public List<List<Integer>> pathSum(TreeNode root, int targetSum) {
+        this.result = new ArrayList<>();
+        helper(root, targetSum, 0, new ArrayList<>());
+        return result;
+    }
+
+    private void helper(TreeNode root, int targetSum, int currSum, List<Integer> path) {
+        //base
+        if (root == null) return;
+
+        //logic
+        currSum += root.val;
+        path.add(root.val);
+
+        if (root.left == null && root.right == null) {
+            if (currSum == targetSum) {
+                result.add(new ArrayList<>(path));
+            }
+        }
+
+        helper(root.left, targetSum, currSum, path);
+        helper(root.right, targetSum, currSum, path);
+
+        path.remove(path.size()-1);
+    }
+}

Problem48.java

@@ -0,0 +1,21 @@
+// Time Complexity : O(N)
+// Space Complexity : O(h)
+
+class Solution {
+    public boolean isSymmetric(TreeNode root) {
+        if(root == null) return true;
+        return helper(root.left, root.right);
+    }
+
+    private boolean helper(TreeNode left, TreeNode right){
+        if(left == null && right == null) return true;
+        if(left == null || right == null){
+            return false;
+        }
+        if(left.val != right.val){
+            return false;
+        }
+
+        return helper(left.left, right.right) && helper(left.right, right.left);
+    }
+}