Paint Board with Undo | Dataford Interview Questions

Implement a Paint class that initializes a board of size m x n and supports methods to print the grid, draw a cell with a given color, undo the previous action, and redo the undone action.

Asked in the technical phone screen stage. Implement the board and history behavior using Python.

Contract

Use paint(m, n, operations). Each operation is a dictionary: {"op": "draw", "row": r, "col": c, "color": color}, {"op": "undo"}, {"op": "redo"}, or {"op": "print"}. Return a list containing the grid produced by each print operation. Empty cells contain ".". A new draw after an undo clears the redo history.

Constraints

1 <= m, n <= 100
1 <= operations.length <= 10^4
Draw coordinates are always valid
Colors are non-empty strings
Undo and redo are no-ops when their corresponding stack is empty

Function Signature

def paint(m, n, operations):

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