# WPC 2017/Round 10

The namesake of this round is *Parallel Universe I* and *Parallel Universe II* by Prasanna Seshadri, held in 2014.^{[1]}

Duration: 50 minutes. Total point value: 650 points. Round winner: Ken Endo and Kota Morinishi (both Japan), 510 points.

### Puzzles[edit]

The puzzles were called "Optimizer"s, but since each puzzle was promised to have a unique solution, they are not traditional Optimisers.

Round note: This round contains 16 puzzles across the same 16 puzzle types that appear in the Evergreens round, but with a slight tweak in the form of an optimization requirement in each puzzle. All puzzles in this round have multiple solutions but have a unique solution if the optimization requirement is met. It is part of solving to use the optimization and achieve a single solution.

1. | Four Winds Optimizer by Rohan Rao, 15 points |

Optimization: Maximize the number of vertical line segments.

2. | Skyscrapers Optimizer by Deb Mohanty, 90 points |

Optimization: Maximize the sum of missing outside clues.

3. | Masyu Optimizer by Deb Mohanty, 20 points |

Optimization: Maximize the number of cells the loop visits.

4. | Arrows Optimizer by Amit Sowani, 25 points |

Optimization: Maximize the number of arrows which point in the given direction. (For example, right(➔).)

5. | Magnets Optimizer by Prasanna Seshadri, 75 points |

Optimization: Minimize the rows and columns, i.e. total directions, containing equal number of positive and negative half-plates.

6. | Star Battle Optimizer by Deb Mohanty, 90 points |

Optimization: Maximize the largest rectangle, in terms of area, without any stars.

7. | Akari Optimizer by Deb Mohanty, 20 points |

Optimization: Maximize the number of light bulbs used.

8. | Tents Optimizer by Deb Mohanty, 20 points |

Optimization: Maximize the length of the longest orthogonally connected chain of tents and trees. A chain is defined as a continuous, non-overlapping, non-branching, non-backtracking path of consecutive cells containing tents or trees in each cell.

9. | Mastermind Optimizer by Deb Mohanty, 20 points |

Optimization: Maximize the four-digit number formed by the series.

10. | Yajilin Optimizer by Ashish Kumar, 30 points |

Optimization: Minimize the number of shaded cells.

11. | Cave Optimizer by Deb Mohanty, 15 points |

Optimization: Some clues are replaced by question marks (?). Maximize the sum of those clues.

12. | Battleships Optimizer by Prasanna Seshadri, 20 points |

Optimization: Some ships of the fleet will NOT appear in the grid, but only ships within the fleet can be used. Maximize the number of cells occupied by ships in the final solution.

13. | Coral Optimizer by Prasanna Seshadri, 50 points |

Optimization: Maximize the number of cells used by the largest un-shaded group in the grid.

14. | Doppelblock Optimizer by Deb Mohanty, 30 points |

Optimization: Minimize the number of white cells adjacent (sharing an edge) to shaded cells.

15. | Different Neighbours Optimizer by Deb Mohanty, 55 points |

Optimization: Minimize the number of 1’s placed in the grid.

16. | Cross Number (Crisscross) Optimizer by Deb Mohanty, 75 points |

Optimization: Some numbers are not found in the grid. Minimize the sum of those numbers.