Leetcode 1579. Remove Max Number of Edges to Keep Graph Fully Traversable

Given an undirected graph with edges usable by Alice-only, Bob-only, or both, compute the maximum number of edges you can remove while still allowing both Alice and Bob to traverse the entire graph (return -1 if impossible). This is a connectivity/union-find problem where you must optimally choose edges—typically by greedily using shared (type-3) edges first—to keep both users' graphs connected and count redundant edges.