Java solution, no need to reverse the list.


  • 4
    public class Solution {
    public List<Integer> postorderTraversal(TreeNode root) {
        List<Integer> R = new LinkedList<Integer>();
        if (root == null) return R;
        Stack<TreeNode> S = new Stack();
        S.push(root);
        while (!S.empty()) {
            TreeNode node = S.pop();
            R.add(0, node.val);
            if (node.left != null) S.push(node.left);
            if (node.right != null) S.push(node.right);
        }
        return R;
    }
    

    }


  • 0
    D

    This method with stack could also be used for Preorder and Inorder without reverse !?


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