from ARC114 ARC114B✅

  • Thoughts.
    • When merging, upstream cannot be selected at the same time.
    • If you choose upstream, you must also choose downstream.
    • SAT-like
      • But it’s a matter of counting up instead of building one, so it’s not.
      • strongly-coupled component decomposition.
      • Isolated loops are “choose all” or “don’t choose all”.
      • Where’s the rest?
        • DAG…
        • No, it’s not a DAG, there’s only one edge from one vertex, so there’s no branching.
      • Isolated loops and trees flowing into loops
        • How to calculate the tree part…
      • No, I thought you couldn’t choose the tree part in the first place.
        • Confluence occurs at the point of flow into the loop, but condition 2 cannot be met.
      • Eventually, the number of loops is 2^N-1 with N as the number of loops.
  • Official Explanation
    • The number of loops and the number of connected components match

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