PDF

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

Theme: High and Low (Note: This puzzle was one of the qualifying round puzzles from this year’s Arlington Puzzle Festival)

Rules: Standard Sudoku rules.

Answer String: Enter the 2nd column from top to bottom, followed by a comma, followed by the 6th column from top to bottom.

Time Standards (highlight to view): Grandmaster = 2:15, Master = 3:15, Expert = 6:30

Solution: PDF

Note: Follow this link for other classic Sudoku. If you are new to this puzzle type, here are our easiest Sudoku to get started on. More classic Sudoku puzzles can be found in The Art of Sudoku, The Art of Sudoku 2 and in our beginner-friendly collection Intro to GMPuzzles by Serkan Yürekli.

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.

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

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

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: Clue Symmetry and Logic

Rules: Standard Cave rules.

Answer String: Enter the length in cells of each of the cave segments from left to right for the marked rows, starting at the top. Separate each row’s entry with a comma.

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

Solution: PDF

Note: Follow this link for other classic Caves. If you are new to this puzzle type, here are our easiest Cave Puzzles to get started on.

Today’s surprise comes from Nikolai Beluhov, a graduate student of mathematical logic who has been sharing some creative puzzle ideas with me recently. Some of them have ended up on his new puzzle blog Puzzled By Titles. This puzzle has become a Sunday Surprise.

Much like a set of Matryoshka dolls, this Fillomino is a puzzle with many layers. Remove the outer border and a new valid Fillomino arises. Keep doing this all the way down to the very center where a 2×2 puzzle awaits. The layers have a wide variety of difficulty and required logical strategies. Can you solve them all?

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between a composite mode for line/edge drawing and a number entry mode.)

Theme: Matryoshka (nesting property) across 5 puzzles

Rules: Standard Fillomino rules.

Answer String: For each puzzle from largest (10×10) to smallest (2×2), enter the numbers placed in each cell along the upper-left to lower-right diagonal in order. Separate each puzzle’s entry by a comma (Your answer will be of the form AAAAAAAAAA,BBBBBBBB,CCCCCC,DDDD,EE).

Solution: PDF

Note: Follow this link for other classic Fillomino and this link for more variations on Fillomino puzzles. If you are new to this puzzle type, here are our easiest Fillomino puzzles to get started on.

Last week’s puzzles are grouped together in this PDF.

This week will have a few surprises and a few less familiar puzzle types. Here are the puzzles you can expect from Monday to Saturday this week (highlight to view):
Monday – Cave by Grant Fikes
Tuesday – Letter Pairs by Palmer Mebane
Wednesday – Sudoku by Thomas Snyder
Thursday – Trid by Serkan Yürekli
Friday – Pentomino Puddles by Serkan Yürekli
Saturday – Neighbors 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

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; an additional shading mode is available by hitting the tab button if that is preferred.)

Theme: Clue Symmetry and Logic

Rules: Blacken some cells and then draw a single non-intersecting loop through all remaining white cells. Outside clues indicate the size of all groups of blackened cells in that row or column in order. There must be at least one white cell between each of these groups. When no clues are given, any number of cells may be shaded in that row/column. Or see here.

Answer String: For each marked column, enter the length in cells of the longest vertical segment. Enter 0 if there are no vertical segments. Enter these values as a single string (eg “230124”).

Time Standards (highlight to view): Grandmaster = 4:15, Master = 7:30, Expert = 15:00

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.