Largest Square Submatrix of all 1's

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:

Restrictions:60s256Mb 1 Score Packages

Feel free to create an issue if you need an extra library from the standard Ubuntu repository.

Name	Version	Description
libc6-dev	2.39-0ubuntu8.7	GNU C Library: Development Libraries and Header Files Contains the symlinks, headers, and object files needed to compile and link programs which use the standard C library.
libclang-common-14-dev	1:14.0.6-19build4	Clang library - Common development package Clang project is a C, C++, Objective C and Objective C++ front-end based on the LLVM compiler. Its goal is to offer a replacement to the GNU Compiler Collection (GCC). . Clang implements all of the ISO C++ 1998, 11, 14 and 17 standards and also provides most of the support of C++20. . This package contains the Clang generic headers.
libclang-common-15-dev	1:15.0.7-14build3	Clang library - Common development package Clang project is a C, C++, Objective C and Objective C++ front-end based on the LLVM compiler. Its goal is to offer a replacement to the GNU Compiler Collection (GCC). . Clang implements all of the ISO C++ 1998, 11, 14 and 17 standards and also provides most of the support of C++20. . This package contains the Clang generic headers.
libclang-common-16-dev	1:16.0.6-23ubuntu4	Clang library - Common development package Clang project is a C, C++, Objective C and Objective C++ front-end based on the LLVM compiler. Its goal is to offer a replacement to the GNU Compiler Collection (GCC). . Clang implements all of the ISO C++ 1998, 11, 14 and 17 standards and also provides most of the support of C++20. . This package contains the Clang generic headers.
libclang-common-17-dev	1:17.0.6-9ubuntu1	Clang library - Common development package Clang project is a C, C++, Objective C and Objective C++ front-end based on the LLVM compiler. Its goal is to offer a replacement to the GNU Compiler Collection (GCC). . Clang implements all of the ISO C++ 1998, 11, 14 and 17 standards and also provides most of the support of C++20. . This package contains the Clang generic headers.
libclang-common-18-dev	1:18.1.3-1ubuntu1	Clang library - Common development package Clang project is a C, C++, Objective C and Objective C++ front-end based on the LLVM compiler. Its goal is to offer a replacement to the GNU Compiler Collection (GCC). . Clang implements all of the ISO C++ 1998, 11, 14 and 17 standards and also provides most of the support of C++20. . This package contains the Clang generic headers.
libclang-common-19-dev	1:19.1.1-1ubuntu1~24.04.2	Clang library - Common development package Clang project is a C, C++, Objective C and Objective C++ front-end based on the LLVM compiler. Its goal is to offer a replacement to the GNU Compiler Collection (GCC). . Clang implements all of the ISO C++ 1998, 11, 14 and 17 standards and also provides most of the support of C++20. . This package contains the Clang generic headers.
libclang-common-20-dev	1:20.1.2-0ubuntu1~24.04.3	Clang library - Common development package Clang project is a C, C++, Objective C and Objective C++ front-end based on the LLVM compiler. Its goal is to offer a replacement to the GNU Compiler Collection (GCC). . Clang implements all of the ISO C++ 1998, 11, 14 and 17 standards and also provides most of the support of C++20. . This package contains the Clang generic headers.
libcrypt-dev	1:4.4.36-4build1	libcrypt development files This package contains the files needed for developing applications that use libcrypt.
libgcc-10-dev	10.5.0-4ubuntu2.1	GCC support library (development files) This package contains the headers and static library files necessary for building C programs which use libgcc, libgomp, libquadmath, libssp or libitm.
libgcc-11-dev	11.5.0-1ubuntu1~24.04.1	GCC support library (development files) This package contains the headers and static library files necessary for building C programs which use libgcc, libgomp, libquadmath, libssp or libitm.
libgcc-12-dev	12.4.0-2ubuntu1~24.04.1	GCC support library (development files) This package contains the headers and static library files necessary for building C programs which use libgcc, libgomp, libquadmath, libssp or libitm.
libgcc-13-dev	13.3.0-6ubuntu2~24.04.1	GCC support library (development files) This package contains the headers and static library files necessary for building C programs which use libgcc, libgomp, libquadmath, libssp or libitm.
libgcc-14-dev	14.2.0-4ubuntu2~24.04.1	GCC support library (development files) This package contains the headers and static library files necessary for building C programs which use libgcc, libgomp, libquadmath, libssp or libitm.
libobjc-13-dev	13.3.0-6ubuntu2~24.04.1	Runtime library for GNU Objective-C applications (development files) This package contains the headers and static library files needed to build GNU ObjC applications.
libssl-dev	3.0.13-0ubuntu3.11	Secure Sockets Layer toolkit - development files This package is part of the OpenSSL project's implementation of the SSL and TLS cryptographic protocols for secure communication over the Internet. . It contains development libraries, header files, and manpages for libssl and libcrypto.
libstdc++-10-dev	10.5.0-4ubuntu2.1	GNU Standard C++ Library v3 (development files) This package contains the headers and static library files necessary for building C++ programs which use libstdc++. . libstdc++-v3 is a complete rewrite from the previous libstdc++-v2, which was included up to g++-2.95. The first version of libstdc++-v3 appeared in g++-3.0.
libstdc++-11-dev	11.5.0-1ubuntu1~24.04.1	GNU Standard C++ Library v3 (development files) This package contains the headers and static library files necessary for building C++ programs which use libstdc++. . libstdc++-v3 is a complete rewrite from the previous libstdc++-v2, which was included up to g++-2.95. The first version of libstdc++-v3 appeared in g++-3.0.
libstdc++-12-dev	12.4.0-2ubuntu1~24.04.1	GNU Standard C++ Library v3 (development files) This package contains the headers and static library files necessary for building C++ programs which use libstdc++. . libstdc++-v3 is a complete rewrite from the previous libstdc++-v2, which was included up to g++-2.95. The first version of libstdc++-v3 appeared in g++-3.0.
libstdc++-13-dev	13.3.0-6ubuntu2~24.04.1	GNU Standard C++ Library v3 (development files) This package contains the headers and static library files necessary for building C++ programs which use libstdc++. . libstdc++-v3 is a complete rewrite from the previous libstdc++-v2, which was included up to g++-2.95. The first version of libstdc++-v3 appeared in g++-3.0.
libstdc++-14-dev	14.2.0-4ubuntu2~24.04.1	GNU Standard C++ Library v3 (development files) This package contains the headers and static library files necessary for building C++ programs which use libstdc++. . libstdc++-v3 is a complete rewrite from the previous libstdc++-v2, which was included up to g++-2.95. The first version of libstdc++-v3 appeared in g++-3.0.
libtbb-dev	2021.11.0-2ubuntu2	parallelism library for C++ - development files TBB is a library that helps you leverage multi-core processor performance without having to be a threading expert. It represents a higher-level, task-based parallelism that abstracts platform details and threading mechanism for performance and scalability. . (Note: if you are a user of the i386 architecture, i.e., 32-bit Intel or compatible hardware, this package only supports Pentium4-compatible and higher processors.) . This package includes the TBB development files.

Back to listJan 4, 2026 18:04

Josu San Martin

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Source Code

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Challenge History

Date	Challenger	Cost	Type	Status
Jul 5, 2026 22:52	Victor Mercklé	10.00	Custom	Solution Broken

Run Statistics

#	Date	Score	Wall Time	CPU User	CPU System	Memory	Error
1	Jul 5, 2026 22:52	0	8,909,370	1,137,000	0	2,117,632	expected "51", got "50 "
2	Jul 5, 2026 22:52	0	8,783,545	1,127,000	0	2,117,632	expected "51", got "50 "
3	Jul 5, 2026 22:52	0	8,856,992	1,134,000	0	2,117,632	expected "51", got "50 "
4	Jan 4, 2026 18:07	2,990	21,846,043	1,196,000	0	2,449,408
5	Jan 4, 2026 18:04	3,235	16,440,894	1,294,000	0	2,445,312
6	Jan 4, 2026 18:07	3,250	17,004,264	1,300,000	0	2,445,312
7	Jan 4, 2026 18:07	3,265	19,583,351	1,306,000	0	2,453,504
8	Jan 4, 2026 18:07	3,508	14,806,899	0	1,403,000	2,457,600
9	Jan 4, 2026 18:04	3,680	15,090,182	1,472,000	0	2,449,408
10	Jan 4, 2026 18:07	3,800	17,295,591	0	1,520,000	2,449,408
11	Jan 4, 2026 18:04	3,820	22,710,632	1,528,000	0	2,449,408
12	Jan 4, 2026 18:07	3,820	14,551,109	1,528,000	0	2,445,312
13	Jan 4, 2026 18:07	3,840	19,221,479	1,536,000	0	2,445,312
14	Jan 4, 2026 18:07	3,850	21,269,430	1,540,000	0	2,535,424
15	Jan 4, 2026 18:04	3,870	17,106,131	0	1,548,000	2,277,376
16	Jan 4, 2026 18:07	3,893	19,656,763	1,557,000	0	2,453,504
17	Jan 4, 2026 18:07	3,898	18,209,983	1,559,000	0	2,449,408
18	Jan 4, 2026 18:07	3,908	16,171,171	1,563,000	0	2,437,120
19	Jan 4, 2026 18:07	3,928	15,286,286	1,571,000	0	2,449,408
20	Jan 4, 2026 18:07	3,935	22,640,155	1,574,000	0	2,445,312
21	Jan 4, 2026 18:04	3,940	22,687,406	1,576,000	0	2,445,312
22	Jan 4, 2026 18:04	3,993	17,463,697	1,597,000	0	2,449,408
23	Jan 4, 2026 18:07	4,213	18,725,337	0	1,685,000	2,453,504
24	Jan 4, 2026 18:07	4,338	17,725,152	1,735,000	0	2,449,408

Model	Intel(R) Xeon(R) CPU E3-1271 v3 @ 3.60GHz
Cores	1