{ 31, 51 }, { 33, 49 }, { 34, 40 }, { 34, 51 }, { 35, 36 },
{ 35, 51 }, { 37, 50 }, { 39, 45 }, { 39, 51 }, { 40, 51 },
{ 44, 51 }, { 47, 50 }, { 47, 51 }, { 48, 51 }, { 49, 50 } };
for (int i = 0; i < edges.length; i++) {
graph.addEdge(edges[i][0], edges[i][1]);
}
graph.clear();
Assert.assertEquals("Size is not empty after clear",
graph.getNodeNum(), 0);