class Graph {

    constructor() {
        this.adjacencyMap = {}
    }

    addVertex(v) {
        this.adjacencyMap[v] = [];
    }

    containsVertex(vertex) {
        return typeof (this.adjacencyMap[vertex]) !== "undefined"
    }

    addEdge(v, w) {
        let result = false
        if (this.containsVertex(v) && this.containsVertex(w)) {
            this.adjacencyMap[v].push(w);
            this.adjacencyMap[w].push(v);
            result = true
        }
        return result
    }



    printGraph() {
        let keys = Object.keys(this.adjacencyMap);
        for (let i of keys) {
            let values = this.adjacencyMap[i];
            let vertex = "";
            for (let j of values)
                vertex += j + " ";
            console.log(i + " -> " + vertex);
        }
    }

}


const example = () => {
    let g = new Graph()
    g.addVertex(1)
    g.addVertex(2)
    g.addVertex(3)
    g.addEdge(1, 2)
    g.addEdge(1, 3)
    g.printGraph()
}