Parse stringified graph (‘a->b,b->c, a->c’) and find all the nodes that can reach a given node

parseGraphAndFindNodesWhichCanReachAGivenNode.js

export const parseGraph = s => s
  .split(',')
  .map(edge => edge.trim().split('->'))
  .reduce((adjacency, [a, b]) => {
    if (!adjacency.has(a)) {
      adjacency.set(a, new Set())
    }
    if (!adjacency.has(b)) {
      adjacency.set(b, new Set())
    }
    adjacency.get(b).add(a)
    return adjacency
  }, new Map())

export const nodesWhichReach = (graph, node) => {
  const visited = new Set()
  if (!graph.has(node)) return visited
  const q = []
  q.push(node)
  
  while (q.length) {
    const currentNode = q.shift()
    visited.add(currentNode)
    for (let n of graph.get(currentNode)) {
      if (!visited.has(n)) q.push(n)
    }
  }
  visited.delete(node)
  return visited
}

/*
const graph = parseGraph('a->b,b->c,q->b,z->q,n->m,m->w,w->p')
nodesWhichReach(graph, 'c') // Set(4) {"b", "a", "q", "z"}
*/