Given a binary tree, return the inorder traversal of its nodes' values.
public class Solution {
public List<Integer> inorderTraversal(TreeNode root) {
List<Integer> res = new ArrayList<>();
// Method 1: Iterative Stack
TreeNode curNode = root;
Stack<TreeNode> stack = new Stack<>();
while (curNode != null || !stack.isEmpty()) {
if (curNode != null) {
stack.push(curNode);
curNode = curNode.left;
}
else {
curNode = stack.pop();
res.add(curNode.val);
curNode = curNode.right;
}
}
return res;
}
}