Top 4 Java constraintprogramming Projects

timefoldsolver
The open source Solver AI for Java, Python and Kotlin to optimize scheduling and routing. Solve the vehicle routing problem, employee rostering, task assignment, maintenance scheduling and other planning problems.
Project mention: Ask HN: Fast data structures for disjoint intervals?  news.ycombinator.com  20240723I written a data structure for grouping intervals into disjoint connected clusters. Each cluster in the data structure is a connected component of the interval space (see https://en.wikipedia.org/wiki/Connected_space for the definition of connected component).
This is useful to determining maximum concurrent use of a resource; for instance, if there are only 3 projectors, a maximum of 3 lessons that require projectors can overlap at any given time.
The basic idea is to use a sorted multiset of each interval's end points, doing case analysis on insertion to determine what interval clusters to merge; removal recomputes the entire cluster the removed range was in, splitting the cluster into two or more when gaps are encountered.
For the implementation, see https://github.com/TimefoldAI/timefoldsolver/blob/main/core...
As a side effect of keeping track of connected clusters, the data structure also keeps track of gaps between clusters (which could be used to find the next availability).
For how it is used in practice, there an example in Timefold's docs:

InfluxDB
Power RealTime Data Analytics at Scale. Get realtime insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in realtime with unbounded cardinality.


timefoldquickstarts
Get started with Timefold quickstarts here. Timefold is the successor of OptaPlanner, by the OptaPlanner team. Optimize the vehicle routing problem, employee rostering, task assignment, maintenance scheduling and other planning problems
Project mention: A Practical Introduction to Constraint Programming Using CPSAT and Python  news.ycombinator.com  20240703Some examples taken from Timefold quickstarts:
 Employee scheduling (https://github.com/TimefoldAI/timefoldquickstarts/tree/stab...)

OptaPlanner
Java Constraint Solver to solve vehicle routing, employee rostering, task assignment, maintenance scheduling, conference scheduling and other planning problems.
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Index
What are some of the best opensource constraintprogramming projects in Java? This list will help you:
Project  Stars  

1  timefoldsolver  853 
2  Choco  685 
3  timefoldquickstarts  198 
4  OptaPlanner  195 