[Sum number && build post order and inorder]

[takchiks]

No description provided.

[super30admin]

Strengths:

• The student uses a hashmap to store inorder indices, which is efficient.
• The recursive approach is correctly implemented with global index tracking for postorder.
• The order of building the tree (right subtree first then left) is correct for postorder.

Areas for improvement:

1. The code includes an unrelated method sumNumbers which is not part of the problem. This should be removed to keep the solution focused and avoid confusion.
2. The variable names could be improved for clarity: postorderIdx is acceptable, but the parameters in helperTree are left and right which represent the start and end indices in the inorder array. It might be better to name them inStart and inEnd to avoid confusion with the postorder array.
3. The initial call to helperTree uses postorderIdx as the right boundary. While it is correct because the arrays have the same length, it would be clearer to use inorder.length-1 directly to make it explicit that the boundaries are for the inorder array.
4. The code lacks comments explaining the approach. Adding comments would make it more understandable.

Suggested corrections:

• Remove the sumNumbers method.
• Change the initial call to: return helperTree(postorder, 0, inorder.length-1);
• Consider renaming parameters in helperTree to inStart and inEnd.