# WPC 2019/Round 6

Duration: 45 minutes. Total point value: 2000 points. Round winner: USA-A (Walker Anderson, Palmer Mebane, Thomas Snyder, Will Blatt), 2900 points.

### Puzzles[edit]

All puzzles in this round were written by Roland Voigt. This is a combination puzzle.

- Cross the Streams, 500 points
- Hydra (Snake with branches), 500 points
- Nurikabe, 500 points
- Tapa, 500 points

These puzzles interact via some additional regions, the patches. The patches have different shapes and no symmetry. Each patch appears exactly once in each puzzle; the placement of the patches is different for each puzzle, furthermore, the patches may be rotated (but not reflected). For each patch, the pattern of shaded and unshaded cells must be identical in all four puzzles.

### Partial Scoring[edit]

For each completely and correctly solved puzzle a team will receive 500 points. If a solution is incomplete or partly incorrect, teams will receive partial points according to the number of shaded cells in the grid. The following formulae will be used:

Score = k × ((# of correctly shaded cells) - (# of incorrectly shaded cells))

(k = 2.1 for Cross the Streams, 2.5 for Hydra, 1.8 for Nurikabe, 1.9 for Tapa)

For each puzzle, the score is rounded down to the nearest integer. If this formula yields a negative result for any puzzle, a team will score 0 points for the puzzle. The scores for the other three puzzles will not be affected.

### Example[edit]

From WPC 2019 IB.