I wonder why Google didn't just go with an off the shelf solution and integrate it instead of building their own solution?
[1] https://www.optaplanner.org/ [2] https://www.minizinc.org/
[1] - https://timefold.ai/ [2] - https://timefold.ai/blog/red-hat-optaplanner-end-of-life-not... [3] - https://docs.timefold.ai/timefold-solver/latest/quickstart/o... [4] - https://github.com/TimefoldAI/timefold-quickstarts/
Google developed its solver a while ago [1] and it has been open sourced more recently. Additionally, it is also a supported solver for Minizinc [2] so you can use it with a well known tool/syntax without having to rely on the python/C++ libraries. However, those give you access to some of the solvers specific features that can help you speed up solving time.
[1] https://developers.google.com/optimization/ [2] https://www.minizinc.org/doc-2.4.3/en/solvers.html#or-tools