Method addVertex

src/13-graph/graph.js:14–19

(vertex)

  }

  addVertex(vertex) {
    if (!this.#vertices.includes(vertex)) {
      this.#vertices.push(vertex);
      this.#adjList.set(vertex, []);
    }
  }

  addEdge(vertex, edge) {
    if (!this.#adjList.get(vertex)) {