Add CP-SAT AddCumulative-like constraint where capacity can be different over periods of time

[alex-klimov]

What language and solver does this apply to?
C++ / CP-SAT

Describe the problem you are trying to solve.
Current implementation of AddCumulative assumes capacity as a constant or LinearExpr. In my case the capacity changes over period of time. Capacity can be pre-computed; it doesn't need to be modeled as a function from t.

No performant solution is found yet with available set of constraints.

Describe the solution you'd like
Override for AddCumulative constraint or a new type of similar constraint, where capacity can be defined as static map from time interval to constant.

Describe alternatives you've considered
No viable performant alternative is discovered within CP-SAT framework yet. Internet search pointed to other people with similar problem, alas I didn't find a solution yet.

Additional context
Depending on the scope of the change I might be able to code this myself and contribute to CP-SAT. I hope that following the implementation path of AddCumulative constraint would be a good guide. And with relatively limited increase of capacity from a constant to an array of constants - new constraint will be performant enough.

[lperron]

1. this is not an issue
2. as indicated in the readme, the various links, the are multiple resources available.
3. this one is explained here: https://github.com/google/or-tools/blob/main/ortools/sat/docs/scheduling.md#cumulative-constraint-with-min-and-max-capacity-profile

[alex-klimov]

Thank you, sir!

When I was looking at this code example, I saw that max constant is used for AddCumulative call and missed the fact that input data has different capacity over t. I am looking closer at the example you have referenced.