Leetcode-Binary Tree Inorder Traversal

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

For example:
Given binary tree {1,#,2,3},

   1
    
     2
    /
   3

return [1,3,2].

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

confused what "{1,#,2,3}" means? > read more on how binary tree is serialized on OJ.

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Solution:

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public List<Integer> inorderTraversal(TreeNode root) {
        List<Integer> nodeList = new ArrayList<Integer>();
        inorderRecur(nodeList,root);

        return nodeList;
        
    }

    public void inorderRecur(List<Integer> nodeList, TreeNode curNode){
        if (curNode==null) return;

        inorderRecur(nodeList,curNode.left);
        nodeList.add(curNode.val);
        inorderRecur(nodeList,curNode.right);

        return;

    }
}