Queue-based topological sort. Develop a topological sort ALGORITHM

that maintains a vertex-indexed array that keeps track of the indegree of each

vertex. Initialize the array and a queue of sources in a single pass through all the

edges, as in Exercise

Then, perform the following operations until the source queue is

empty:

Remove a source from the queue and label it.

Decrement the entries in the indegree array corresponding to the destination

vertex of each of the removed vertexs edges.

If decrementing any entry causes it to become 0, insert the corresponding vertex

onto the source queue