Traverse Tree Columns with Stable Row Ties
Company: Bloomberg
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Other
### Problem
Return node values column by column from left to right, and top to bottom within each column. The root has column zero; left and right children shift by -1 and +1. For nodes sharing row and column, preserve their left-to-right tree order, not sorted value order. Keep the TreeNode* root API.
```cpp
vector<vector<int>> verticalOrder(TreeNode* root);
```
### Examples
```text
root = [8,4,12,2,7,6,14] -> [[2],[4],[8,7,6],[12],[14]]
root = [] -> []
```
### Constraints
- There are 0 through 100 nodes.
- Values lie in [-100,100].
Overview: Traverse Tree Columns with Stable Row Ties. Return node values column by column from left to right, and top to bottom within each column. The root has column zero; left and right children shift by -1 and