Largest Square Submatrix of all 1's NoSIMD_C#

Find the largest square submatrix consisting entirely of 1s as fast as possible.

Input

A 10,000 x 10,000 matrix of uint8 values (0 or 1) on STDIN.

0, 1, 0, 1, 1
0, 1, 1, 1, 1
0, 0, 1, 0, 0
1, 0, 1, 1, 0

Output

Print the side length of the largest all-ones square submatrix to STDOUT. The answer is guaranteed to be greater than 1.

For the example above, the output is:

2
Back to listJan 5, 2026 05:22Josu San MartinJosu San MartinError
Source Code

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Challenge History
DateChallengerCostTypeStatus
May 17, 2026 13:43M-Rochat10.00CustomSolution Broken
Run Statistics
#DateScoreWall TimeCPU UserCPU SystemMemoryError
1May 17, 2026 14:01010,879,367862,00002,117,632expected "269", got "100 "
2May 17, 2026 14:0109,988,161854,00002,117,632expected "269", got "100 "
3May 17, 2026 14:01010,032,224854,00002,117,632expected "269", got "100 "
4Jan 5, 2026 05:223,70322,209,86901,481,0002,437,120
5Jan 5, 2026 05:233,70321,144,07101,481,0002,449,408
6Jan 5, 2026 05:233,71816,700,9961,487,00002,445,312
7Jan 5, 2026 05:223,73316,956,6771,493,00002,535,424
8Jan 5, 2026 05:233,74318,471,2061,497,00002,535,424
9Jan 5, 2026 05:223,79820,017,9911,519,00002,441,216