Biggest Solid Panel Block

Hard

An LED board is given as a grid panel: each cell is the string "1" if that pixel works and is lit, or "0" if it has gone dark. A designer wants to show a picture in a rectangular area where **every** pixel is lit. Return the area (number of cells) of the largest such rectangle whose sides follow the rows and columns of the board. If no pixel is lit, return 0.

Example 1

panel=[['1', '1', '0', '1'], ['1', '1', '1', '1'], ['0', '1', '1', '1']] → 6

The largest fully lit rectangle covers columns 1–3 in rows 1–2 (0-based): 2 × 3 = 6 pixels.

Example 2

panel=[['0', '0'], ['0', '0']] → 0

No pixel is lit, so the answer is 0.

Example 3

panel=[['1', '0', '1', '1', '1']] → 3

With a single row, the best block is the run of three lit pixels.

Constraints

1 ≤ len(panel), len(panel[i]) ≤ 500
All rows have the same length
panel[i][j] is "0" or "1"

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Stack Array Dynamic Programming Matrix Monotonic Stack

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Input

panel=[['1', '1', '0', '1'], ['1', '1', '1', '1'], ['0', '1', '1', '1']]

Expected

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