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Hydra (Ambiguous) (1261)
Instruction:
Locate a "hydra" in the grid. The hydra is a region of orthogonally-connected cells. The hydra does not contain any 2×2 group of cells. All cells that are not part of the hydra must be connected orthogonally (through other non-hydra cells) to the edge of the grid (in other words, the hydra cannot loop or touch itself diagonally). No hydra cell can share edges with exactly four other hydra cells.
The hydra cannot go through any cells marked with '×'. Every hydra cell that shares an odd number of edges with other hydra cells is marked with a black rounded rectangle, and no other cells can have a black rounded rectangle.
Numbers outside the grid, if given, indicate how many cells in that row or column are occupied by the hydra.