refactor: drop Boost.Algorithm

[Becheler]

Before submitting

• This PR targets the develop branch.
• I searched for an existing PR or issue covering the same change.
• My contribution is licensed under the Boost Software License 1.0.

Type of change

• Bug fix
• New feature or API addition
• Refactor (no behavior change)
• Documentation
• Build, CI, or tooling
• Other (specify below)

Does this PR introduce a breaking change?

• Yes (describe migration impact below)
• No

What this PR does

• topology.hpp: replaced algorithm/minmax.hpp include with <algorithm>
• howard_cycle_ratio.hpp and bc_clustering.hpp: replaced boost::first_max_element with an explicit first-max loop
• graphviz.hpp: replaced boost::algorithm::replace_all with a quote-escape loop
• read_graphviz_new.cpp: replaced boost::algorithm::to_lower_copy with std::transform
• parallel_edges_loops_test.cpp and all_planar_input_files_test.cpp: replaced boost::split with a loop
• Added test/bc_clustering_test.cpp: guards the max-edge pick (bridge removed, graph splits into 2 components)

std::max_element is not usable here: it requires a ForwardIterator, and libc++ enforces that with a hard static_assert, but BGL's edge iterators declare a category that does not satisfy it. boost::first_max_element had no such check, so the replacement is a short explicit loop instead.

Motivation

Boost.Algorithm adds 30 dependencies for something that STL and short loops can do easily.

Testing

Checklist

• Existing tests pass (b2 in the test/ directory).
• New behavior is covered by a test, or this is a docs / build / refactor change.
• Documentation was updated if user-facing behavior changed.
• No new compiler warnings on the platforms I built against.

[github-actions]

Boost dependency footprint vs develop (auto-generated).
PR run 34031987491 vs develop run 33983571785 (ca7d38dc74).

Header-inclusion weights (graph files pulling each direct dependency in):

Dependency	develop	PR	Δ
algorithm	5	0	-5

Transitive Boost modules: 49 → 47 (-2)

• removed: algorithm, exception

[github-actions]

Compiler-warning counts vs develop (auto-generated).
PR run 34031987477 vs develop run 33983571789 (ca7d38dc74).

Job	Baseline	After	Delta
macos (clang, 14)	439	444	+5
macos (clang, 17)	402	407	+5
macos (clang, 20)	402	407	+5
ubuntu (clang-19, 14)	439	444	+5
ubuntu (clang-19, 17)	402	407	+5
ubuntu (clang-19, 20)	402	407	+5
ubuntu (clang-19, 23)	402	407	+5
ubuntu (gcc-14, 14)	373	373	0
ubuntu (gcc-14, 17)	369	369	0
ubuntu (gcc-14, 20)	369	369	0
ubuntu (gcc-14, 23)	369	369	0
windows_msvc_14_3 (msvc-14.3)	961	961	0

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[jeremy-murphy]

std::max_element - cppreference.com https://share.google/cBYeq3gW04DAipAiH
?

[Becheler]

That was my first try but it fails compilation because of a conflict between requirements of boost versus stl iterators (ForwardIterator).

[Becheler]

Passing to std would be going back to the problem described in #175 and #190

[jeremy-murphy]

Ehhh, I see, thanks.