You know BFS, DFS, Dijkstra, and basic tree algorithms. This section pushes into territory that appears in Codeforces - rated problems.
You'll work through bridge finding for connectivity, segment tree optimization for Dijkstra, LCA for tree path queries, and combining MST with tree operations. These techniques let you solve problems that basic graph algorithms can't handle efficiently.
By the end, you'll recognize when a graph problem needs these advanced tools.