# 2. Connected Graph & Topologic Sorting

- [Search Graph Nodes](/algo/bfs/2.-connected-graph-and-topologic-sorting/search-graph-nodes.md): ID: 618; medium
- [Graph Valid Tree](/algo/bfs/2.-connected-graph-and-topologic-sorting/graph-valid-tree.md): ID: 178; medium
- [Connected Component in Undirected Graph](/algo/bfs/2.-connected-graph-and-topologic-sorting/connected-component-in-undirected-graph.md): ID: 431; medium
- [Topological Sorting](/algo/bfs/2.-connected-graph-and-topologic-sorting/topological-sorting.md): ID: 127; medium
- [Course Schedule](/algo/bfs/2.-connected-graph-and-topologic-sorting/course-schedule.md): ID: 615; medium
- [Course Schedule II](/algo/bfs/2.-connected-graph-and-topologic-sorting/course-schedule-ii.md): ID: 616; medium
- [Sequence Reconstruction](/algo/bfs/2.-connected-graph-and-topologic-sorting/sequence-reconstruction.md): ID: 605; medium
- [Clone Graph](/algo/bfs/2.-connected-graph-and-topologic-sorting/clone-graph.md): ID: 137; medium
- [Alien Dictionary](/algo/bfs/2.-connected-graph-and-topologic-sorting/alien-dictionary.md): ID: 892; hard