There is a graph that consists of vertices (industrial installations) and edges flows of raw materials, intermediates and products between this nodes.
I need some kind of algorithm for “traversing” this graph from source nodes to consumer nodes.

The key requirement for the algorithm is that I can move from a certain node of the graph to the next one only if I have already visited this node before with all entering streams entering ( Edges of the graph)

For example. Suppose I have node A and B (sources) that are connected to node C (intermediate), and node C is connected to node D (consumer). The algorithm must first go from A to C, then from B to C, and only then from C to D. In other words, some calculations must be performed in node C and they can be done only after I have already visited it with all incoming flows earlier, then these calculations are used to evaluate the output C flow.

What mathematical algorithm will allow to do this?

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