Bipartite graph with edges as vertices

• A graph can be a bipartite graph with edges (and similar vertex-to-vertex relationships) as vertices

  • That's still fine in terms of finding a connected component.

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• This conversion is beneficial when it is expensive to build an edge in Yang

  • For example, "an edge is subtracted when a vertex has a sequence of length m and the two vertices have a number in common."
    • It costs O(V^2M).
    • O(VM) when the number is also a vertex.
    • The number of vertices increases, but it is not important because UnionFind is almost of constant order
    • It is not generally true that the number of edges is reduced
      • The case with fewer constraints codefestival_2016_final_c.

• problem transformation

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