✅💯🔥Simple Code🚀📌|| 🔥✔️Easy to understand🎯 || 🎓🧠Beats 100%🔥|| Beginner friendly💀💯
Intuition\n Describe your first thoughts on how to solve this problem. \n\n# Approach\n Describe your approach to solving the problem. \n\n# Complexity\n- Time 
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\n/**\n * Definition for a binary tree node.\n * public class TreeNode {\n *     int val;\n *     TreeNode left;\n *     TreeNode right;\n *     TreeNode() {}\n *     TreeNode(int val) { this.val = val; }\n *     TreeNode(int val, TreeNode left, TreeNode right) {\n *         this.val = val;\n *         this.left = left;\n *         this.right = right;\n *     }\n * }\n */\nclass Solution {\n    List<Integer> ans = new ArrayList<>();\n    public List<Integer> preorderTraversal(TreeNode root) {\n        preorder(root);\n        return ans;\n    }\n    public void preorder(TreeNode node){\n        if(node==null){\n            return;\n        }\n        ans.add(node.val);\n        preorder(node.left);\n        preorder(node.right);\n    }\n}\n```\n\n![7be995b4-0cf4-4fa3-b48b-8086738ea4ba_1699897744.9062278.jpeg](https://assets.leetcode.com/users/images/fe5117c9-43b1-4ec8-8979-20c4c7f78d98_1721303757.4674635.jpeg)
['Stack', 'Tree', 'Depth-First Search', 'C', 'Binary Tree', 'Python', 'C++', 'Java']