94. Binary Tree Inorder Traversal #

Problem Statement: #

Given the root of a binary tree, return the inorder traversal of its nodes' values.

Example 1: #

Input: root = [1,null,2,3]
Output: [1,3,2]

Example 2: #

Input: root = []
Output: []

Example 3: #

Input: root = [1]
Output: [1]

Constraints: #

• The number of nodes in the tree is in the range [0, 100].
• -100 <= Node.val <= 100

Follow up: Recursive solution is trivial, could you do it iteratively?

Solution: #

public class BinaryTreeInorderTraversal {
    List<Integer> list = new ArrayList<>();

    public List<Integer> inorderTraversal(TreeNode root) {
        if (root == null)
            return list;
        inorderTraversal(root.left);
        list.add(root.val);
        inorderTraversal(root.right);
        return list;
    }
}

... #