Stable topological sort

Question

Let say I have a graph where the nodes is stored in a sorted list. I now want to topological sort this graph while keeping the original order where the topological order is

Answer 1

The depth-first search algorithm on Wikipedia worked for me:

const assert = chai.assert;

const stableTopologicalSort = ({
  edges,
  nodes
}) => {
  // https://en.wikipedia.org/wiki/Topological_sorting#Depth-first_search
  const result = [];
  const marks = new Map();

  const visit = node => {
    if (marks.get(node) !== `permanent`) {
      assert.notEqual(marks.get(node), `temporary`, `not a DAG`);
      marks.set(node, `temporary`);
      edges.filter(([, to]) => to === node).forEach(([from]) => visit(from));
      marks.set(node, `permanent`);
      result.push(node);
    }
  };

  nodes.forEach(visit);
  return result;
};

const graph = {
  edges: [
    [5, 11],
    [7, 11],
    [3, 8],
    [11, 2],
    [11, 9],
    [11, 10],
    [8, 9],
    [3, 10]
  ],
  nodes: [2, 3, 5, 7, 8, 9, 10, 11]
};

assert.deepEqual(stableTopologicalSort(graph), [5, 7, 11, 2, 3, 8, 9, 10]);