static getEdgeList(adjacencyMatrix) {
    let length = adjacencyMatrix.length;
    let edgeList = Array();
    var i = length - 1;

    while (i--) {
      var j = length;

      while (j--) {
        if (adjacencyMatrix[i][j] === 1) {
          edgeList.push([i, j]);
        }
      }
    }

    return edgeList;
  }
Returns an edge list constructed form an adjacency matrix.

@param {Array[]} adjacencyMatrix An adjacency matrix.
@returns {Array[]} An edge list. E.g. [ [ 0, 1 ], ..., [ 16, 2 ] ]