I am trying to reduce my problem to a max flow problem so I can run the max flow algorithm on this problem. But there are some things that I am missing while transforming my problem.
My problem is:
- there are classes with a maximum capacity
- there are students and their wish-list that includes 5 classes that they want
- students can select at most 5 classes.
And the goal is:
- to maximize number of classes that students enroll.
If I put students and classes as vertices (please see image above), then put a source node s that has an edge to each student and a sink node t that has an edge to each classes, what will be the edge costs?
- edge cost between classes and sink node t or
- edge cost between source node s and and students
Are the following assumptions correct?
I think the edge between students and classes cost should be 1. Because a student can only enroll once to a class in a term. I think edge cost between classes and the sink node t will be the maximum capacity of a class.
I don't have an idea about edge costs between source node s and students nodes.
And at the end, after arranging, do we just need to run max flow algorithm?
Best Answer
I think that a max flow from S to any student of 5, and max flow of capacity from each class to T and 1 from each student to each class would satisfy your requirements. BTW, that is not an edge cost but rather an edge flow capacity.