1DFS categorized directed graph 2tree: 0 --> 2 3tree: 2 --> 1 4back: 1 --> 1 5tree: 1 --> 3 6back: 3 --> 1 7tree: 3 --> 4 8back: 4 --> 0 9back: 4 --> 1 10forward or cross: 2 --> 3 11 12BFS categorized directed graph 13tree: 0 --> 2 14tree: 2 --> 1 15tree: 2 --> 3 16cycle: 1 --> 1 17cycle: 1 --> 3 18cycle: 3 --> 1 19tree: 3 --> 4 20cycle: 4 --> 0 21cycle: 4 --> 1 22