Created 0144-Binary-Tree-Preorder-Traversal.java

Author: RakeshTirumala

java/0144-Binary-Tree-Preorder-Traversal.java

@@ -0,0 +1,16 @@
+class Solution {
+    public List<Integer> preorderTraversal(TreeNode root) {
+        List<Integer> res = new ArrayList<>();
+        Stack<TreeNode> stack = new Stack<>();
+        TreeNode current = root;
+        while(current!=null || !stack.isEmpty()){
+            while(current!=null){
+                res.add(current.val);
+                stack.add(current.right);
+                current = current.left;
+            }
+            current = stack.pop();
+        }
+        return res;
+    }
+}