class Graph {

    constructor(numVertices) {

        this.numVertices = numVertices;

        this.adjMatrix = Array.from({ length: numVertices }, () => Array(numVertices).fill(false));

    }

​

    addEdge(i, j) {

        this.adjMatrix[i][j] = true;

        this.adjMatrix[j][i] = true;

    }

​

    removeEdge(i, j) {

        this.adjMatrix[i][j] = false;

        this.adjMatrix[j][i] = false;

    }

​

    toString() {

        let s = "";

        for (let i = 0; i < this.numVertices; i++) {

            s += i + ": ";

            for (const j of this.adjMatrix[i]) {

                s += (j ? 1 : 0) + " ";

            }

            s += "\n";

        }

        return s;

    }

}

​