PDF

or solve online (using our beta test of Penpa-Edit tools).

Theme: Logical

Author/Opus: This is the 1st puzzle from guest contributor Ravi Kumar Macherla who also contributed several Masyu to the book “The Art of Puzzles”. You can find more of Ravi’s puzzles on his relatively new blog site.

Rules: Place each of the indicated shapes into the grid (rotations allowed, but not reflections) so that no two shapes touch even at a corner. Numbers outside the grid indicate the product of the lengths of all white cell groups in that row/column. Or see here:

Answer String: Enter the number of cells in each group (both black and white) in order in the marked rows/columns. In the example, this answer is “231,1221”

Time Standards (highlight to view): Grandmaster = 4:15, Master = 7:00, Expert = 14:00

Solution: PDF

PDF

or solve online (using our beta test of Penpa-Edit tools using a composite mode where left click inside cell shades square, left click + drag draws line segment, right click inside cell adds dot, and right click on cell edge adds an x.)

Theme: Clue Symmetry

Rules: Place some blocks of three hexagons connected in a line (briquets) into the grid so that they do not overlap themselves or the numbered cells. For each numbered cell, the top clue indicates how many of the surrounding cells containing a briquet segment; the bottom clue indicates how many different briquets are in the surrounding cells. All cells that are not covered by briquets, including the numbered cells, must be part of a single connected group. Or see this example from the WPC instruction booklet.

Answer String: For each marked row, enter the length in cells of each group of connected cells that are part of briquets. Separate each row’s entry with a comma (eg “5,16,33,14”).

Time Standards (highlight to view): Grandmaster = 5:30, Master = 8:30, Expert = 17:00

Solution: PDF

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between shading mode and the linex mode where left click+drag draws lines and right click marks X’s)

Theme: “Hard” Practice (this was a WPC puzzle style) — in contrast to this post.

Rules: Place each of the 11 pentominoes into the grid exactly once, with rotations and reflections allowed, to form a valid “Coral”. In a Coral puzzle, all blackened areas are connected, but no group of 2×2 cells is entirely blackened. Also, there are no unshaded areas enclosed by the coral (meaning each unshaded cell must have a path through its edges with other unshaded cells to a border). Numbers outside the grid indicate the lengths of groups of shaded cells in that row/column, but not necessarily in order.

Or see this example from the 22nd WPC instruction booklet.

Answer String: Enter the identities of the pentominoes (one capital letter for each, even if in multiple cells) appearing in the marked rows from left to right (eg “ILN,WVXT”).

Time Standards (highlight to view): Grandmaster = 10:00, Master = 20:00, Expert = 40:00

Solution: PDF

PDF

or solve online (using our beta test of Penpa-Edit tools using a composite mode where left click inside cell shades square, left click + drag draws line segment, right click inside cell adds dot, and right click on cell edge adds an x.)

Theme: Clue Symmetry and Logic

Rules: Locate some blocks in the grid, either 1×2 or 1×3 in size, with each block containing one of the given numbers. Each block is allowed to move in its long direction, stopped only by an edge of the grid or another block. A block’s number must indicate the total possible movement of the block. Or see here.

Answer String: Enter the size of consecutive groups of cells that belong to blocks in each marked row from left to right, separating each row’s entry with a comma (ie “151,22,44,22”).

Time Standards (highlight to view): Grandmaster = 3:15, Master = 5:30, Expert = 11:00

Solution: PDF

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to shift between shading mode and the linex mode where left click+drag draws lines and right click marks X’s)

Theme: “Easy” Practice (this was a WPC puzzle style)

Rules: Place each of the 11 pentominoes into the grid exactly once, with rotations and reflections allowed, to form a valid “Coral”. In a Coral puzzle, all blackened areas are connected, but no group of 2×2 cells is entirely blackened. Also, there are no unshaded areas enclosed by the coral (meaning each unshaded cell must have a path through its edges with other unshaded cells to a border). Numbers outside the grid indicate the lengths of groups of shaded cells in that row/column, but not necessarily in order.

Or see this example from the 22nd WPC instruction booklet.

Answer String: Enter the identities of the pentominoes (one capital letter for each, even if in multiple cells) appearing in the marked rows from left to right (eg “ILN,WVXT”).

Time Standards (highlight to view): Grandmaster = 4:15, Master = 6:30, Expert = 13:00

Solution: PDF

Editorial Note: Many solvers can confuse Coral with another puzzle type with similar spelling. An easy way to remember the difference is that Cave has no R’s and also has no 2×2 Region constraint. Coral puzzles, with an R, do have this region constraint. The other general rules (about not enclosing white spaces and having a single shaded group) are shared between Cave and Coral puzzles.

PDF

or solve online (using our beta test of Penpa-Edit tools using a composite mode where left click inside cell shades square, left click + drag draws line segment, right click inside cell adds dot, and right click on cell edge adds an x.)

Theme: Railroad Crossing (“Tren” means train in Turkish.)

Rules: Locate some blocks in the grid, either 1×2 or 1×3 in size, with each block containing one of the given numbers. A block’s number must indicate the total possible movement of the block along either direction in its long direction, where it is blocked only by an edge of the grid or another block. Or see here.

Answer String: Enter the size of consecutive groups of cells that belong to blocks in each marked row from left to right, separating each row with a comma (ie 151,22,44,22).

Time Standards (highlight to view): Grandmaster = 5:00, Master = 7:30, Expert = 15:00

Solution: PDF