This is a Melon puzzle. (23 – Sudoku +/- 4)

Sudoku +/- 4 by Palmer Mebane

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between Number entry mode and a shading mode to help track complete clues.)

Theme: Clue Symmetry, and Very Hard WPC Practice

Rules: Variation of Sudoku. Place integers from -4 to 4 into each cell so that each row, column, and region contains each integer from -4 to 4 exactly once. The numbers outside the grid represent the sum of all integers between that clue and the zero in that row/column. Some cells inside the grid already contain an integer but no sign is given. It is part of the puzzle to determine if these values are positive or negative. An example using -2 to 2 from the WPC instructions is here.

Answer String: Enter the numbers (ignoring sign) from left to right in the marked rows, separating each row with a comma (eg “123401234,431023412”).

Time Standards (highlight to view): Grandmaster = 10:00, Master = 16:00, Expert = 32:00

Solution: PDF

The Puzzle Robot #24 – Tapa-like Loop

Tapa-like Loop by Serkan Yürekli

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or solve online (using our beta test of Penpa-Edit tools in linex mode where left click+drag draws lines and right click marks X’s on edges)

Theme: Clue Symmetry and Logic

Rules: In this variation of Tapa, the wall is in the form of a single non-intersecting loop. Clues inside the grid represent the number of neighboring cells visited by the loop; if there is more than one number in a cell, each number should be represented with a separate loop segment. There is no 2×2 rule of Tapa in this puzzle. This example image should help:

Tapa-like Loop Example by Serkan Yürekli

Answer String: Enter the length in cells of the horizontal loop segments from left to right in the marked rows, starting at the top. Separate each row’s entry with a comma. For the example, this would be “11,12”.

Time Standards (highlight to view): Grandmaster = 1:30, Master = 2:15, Expert = 4:30

Solution: PDF

Note: Follow this link for other Tapa-Like Loop puzzles. If you are new to this puzzle type, here are our easiest Tapa puzzles to get started on.

Dr. Sudoku Prescribes #146 – Skyscrapers (Sum)

Sum Skyscrapers by Thomas Snyder

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

Theme: Nine High

Rules: Variant of Skyscrapers rules. The numbers outside the grid represent the sum of the buildings seen in that row or column. For example, if a row is 12534, the clue from the left would be an 8 (1+2+5) and from the right would be a 9 (4+5).

Answer String: Enter the 2nd row from left to right, followed by a comma, followed by the 5th row from left to right.

Time Standards (highlight to view): Grandmaster = 1:00, Master = 2:15, Expert = 4:30

Solution: PDF

This is a Melon puzzle. (22 – Hexa Briquets)

Hexa Briquets by Palmer Mebane

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

The Puzzle Robot #23 – Easy as Japanese Sums

Easy as Japanese Sums by Serkan Yürekli

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or solve online (using our beta test of Penpa-Edit tools; use tab to shift between number entry and shading modes.)

Theme: Clue Symmetry and Logic

Rules: Hybrid of Easy as ABCD and Japanese Sums puzzle types. Fill some cells with digits 1-5 so that each row and column contains each digit from 1 to 5 exactly once as well as two empty cells. Numbers outside the grid indicate the sum of all digits in the first connected group in that direction as in a Japanese Sums puzzle. For example, the row X345X12 could have a 12 clue on the left or a 3 on the right. Or see here.

Answer String: Enter the marked rows from left to right, separating the two rows by a comma. Use an X (capital letter) for each empty square.

Time Standards (highlight to view): Grandmaster = 3:30, Master = 4:15, Expert = 8:30

Solution: PDF

Note: Follow this link for other Japanese Sums puzzles.

This is a Melon puzzle. (21 – Neighbors)

Neighbors by Palmer Mebane

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

Theme: WPC Practice

Rules: Place a digit 1, 2, or 3 into each empty cell so that each digit appears exactly three times in each row and column. All cells are either white or gray. A digit in a white cell must share an edge with at least one cell containing the same digit. A digit in a gray cell cannot share an edge with any cell containing the same digit.

Answer String: Enter the digits from left to right in the marked rows, separating the rows with a comma.

Time Standards (highlight to view): Grandmaster = 10:00, Master = 15:00, Expert = 30:00

Solution: PDF

The Puzzle Robot #21 – Trid

Trid by Serkan Yürekli

PDF

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

Theme: Logical

Rules: Place a digit from 1-7 into each circle so that no digit repeats within any straight line. The clues given inside some triangles represent the sum of the digits in the triangle’s three vertices. Or see here.

Answer String: Enter the digits in the marked lines in the direction of the arrows, separating the two lines with a comma.

Time Standards (highlight to view): Grandmaster = 3:45, Master = 4:45, Expert = 9:30

Solution: PDF

From the Foxger’s Den #69: Letter Pairs

Editorial Note: “Double Word Puzzle Score?” Inspired to write his own letter pairs after solving Palmer’s (see previous post), Grant contributed this very fun submission which we are also publishing today for a rare double puzzle day.

Letter Pairs by Grant Fikes

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between a letter entry mode and a shading mode to mark off the clues.)

Theme: Months

Rules: Place the 12 words into the grid, one letter per cell, so they can be read from left to right or from top to bottom, without crossing or overlapping each other. A dot between two cells indicates that both cells must contain the same letter. All possible dots are given. Or see this example from the WPC instructions.

Answer String: For each column from left to right, enter the number of unused cells in that column (eg “3510563449”).

Time Standards (highlight to view): Grandmaster = 2:30, Master = 4:00, Expert = 8:00

Solution: PDF

This is a Melon puzzle. (20 – Letter Pairs)

Letter Pairs by Palmer Mebane

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between a letter entry mode and a shading mode to mark off the clues.)

Theme: One-Point Letters

Rules: Place the 9 words into the grid, one letter per cell, so they can be read from left to right or from top to bottom, without crossing or overlapping each other. A dot between two cells indicates that both cells must contain the same letter. All possible dots are given. Or see this example from the WPC instructions.

Answer String: For each column from left to right, enter the number of unused cells in that column (eg “3510563449”).

Time Standards (highlight to view): Grandmaster = 1:30, Master = 4:30, Expert = 9:00

Solution: PDF

This is a Melon puzzle. (19 – Pento Coral)

Pento Coral by Palmer Mebane

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