094 - Binary Tree Inorder Traversal

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:

Java

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;
    }
}

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