in order rec and iter

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    public List<Integer> inorderTraversal(TreeNode root) {
        //stack to traverse the tree
        Deque<TreeNode> stack = new ArrayDeque<TreeNode>();
        //list to hold the inorder traversal
        List<Integer> list = new LinkedList<Integer>();
        // if (root != null){
        //  recInorder(list, root);
        // }

        //traversal temp var
        TreeNode curr = root;
        //while loop to fill out the list
        while (curr != null || !stack.isEmpty()){
            //first push to the stack all of the root's left nodes until theres a null
            while(curr != null){
                stack.push(curr);
                curr = curr.left;
            }

            //once you've hit the bottom of the left subtree, get the last
            //one that was put it
            if (!stack.isEmpty()){
                curr = stack.pop();
            }
            //and put it in the list
            list.add(curr.val);
            //then shift over to that node's right subtree and begin the process of going
            //down the left subtree again (if there are any right/left subtrees)
            //tho the if not nulls in the whiles deal with this
            curr = curr.right;
        }

        return list;
    }

    public void recInorder(List<Integer> list, TreeNode root){
        if (root.left != null){
            recInorder(list, root.left);
        }
        list.add(root.val);
        if (root.right != null){
            recInorder(list, root.right);
        }
    }
}