Masyu

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Rules[edit]

Masyu Example.png Masyu Example Solution.png

Draw a single, non-intersecting loop that passes orthogonally through all circled cells. The loop must go straight through the cells with white circles, with a turn in at least one of the cells immediately before or after each white circle. The loop must make a turn in all the black circles but must go straight in both cells immediately before and after each black circle.

(Rules and example from PGP IB)

History of the puzzle[edit]

First appeared on Nikoli volume 90 (2000) under the name of "白真珠黒真珠" ("White pearls, black pearls"). Invented by アセトニトリル ("Acetonitril"). Renamed to "ましゅ" ("Masyu") in volume 103 (2003).

This puzzle was suggested as a modified version of "真珠の首飾り" ("Pearl earring") by 矢野龍王 ("Yano Ryuoh"), first appeared in 1999, where only white circles were present.

Variants[edit]

Deformable Masyu[edit]

Deformable Masyu Example.png Deformable Masyu Example Solution.png

Invented by Serkan Yürekli (Turkey) in 2009. First appeared on Oğuz Atay Puzzle Contest 6. The name was given by Kamer Alyanakyan (Turkey), according to Serkan's website.

Draw a single, non-intersecting loop that passes orthogonally through all circled cells. The loop must go straight through the cells with white circles, with a turn in at least one of the cells immediately before or after each white circle. The loop must make a turn in all the black circles but must go straight in both cells immediately before and after each black circle.

White circles can be shaded to transform them into black circles. To determine which circles to shade is part of the puzzle.

(Example from WPC 2019 IB)

Regional Masyu[edit]

Regional Masyu Example.png Regional Masyu Example Solution.png

Invented by Swaroop Guggilam (India) in 2012. You can see one of Swaroop's first Regional Masyus in here.

Draw a single, non-intersecting loop that passes orthogonally through all circled cells. The loop must go straight through the cells with white circles, with a turn in at least one of the cells immediately before or after each white circle. The loop must make a turn in all the black circles but must go straight in both cells immediately before and after each black circle.

Additionally, in each region, the loop makes the same number of turns. How many turns it makes is left for solvers to determine.

(Example from WPC 2018 IB)

  • For a puzzle in WPC 2018/Round 11, the number of turns in each region was given. (4 turns)

Syuma[edit]

Syuma Example.png Syuma Example Solution.png

Introduced by Prasanna Seshadri (India). First appeared on Parallel Universe II – Inversion Invasion, held in April 2014. [1]

Draw a closed loop passing through centres of cells horizontally or vertically, passing through all circles. The loop must go straight through the cells with white circles, with a turn in both cells immediately before/after each white circle. The loop must make a turn in all the black circles, but must go straight in at least one of the cells immediately before/after each black circle.

(Rules and example from WPC 2017 IB)

Full Masyu[edit]

Full Masyu Example.png Full Masyu Example Solution.png

First appeared on WPC 2016/Round 4 ("Full Classics" round). The author of the puzzle was Matej Uher (Slovakia).

Shade some cells and draw a Masyu loop through the remaining cells to get a valid Masyu solution:

Shade some cells in the grid. Then, draw a single loop that travels horizontally and vertically between cell centres and passes through each circle. The loop must go straight through white circles but must turn in at least one of the adjacent cells. The loop must turn in the black circles and go straight through both following cells. The loop cannot pass through the shaded cells.

(Rules and example from WPC 2016 IB)

Myopia Masyu[edit]

Myopia Masyu Example.png Myopia Masyu Example Solution.png

First appeared on WPC 2016/Round 10, a Myopia-related variant round. The author of the puzzle was Matej Uher (Slovakia).

Draw a single, non-intersecting loop that passes orthogonally through all circled cells. The loop must go straight through the cells with white circles, with a turn in at least one of the cells immediately before or after each white circle. The loop must make a turn in all the black circles but must go straight in both cells immediately before and after each black circle.

The arrows point at all of the closest cells that black or white Masyu circles could be placed on. No loop segment can be placed in a cell already containing an arrow.

(Example from WPC 2016 IB. Green cells denote all cells on which it is possible to place Masyu circles; they are just for illustrative purposes.)

Liar Masyu[edit]

Liar Masyu Example.png Liar Masyu Example Solution.png

First appeared on WPC 2018/Round 13. The author of the puzzle was Petr Vejchoda (Czech Rep.).

Standard Masyu rules apply. However, the circles are not in their correct positions. Solvers must move every circle to a horizontally or vertically adjacent cell and then solve the puzzle.

(Example from WPC 2018 IB)

Appearances in the past WPCs[edit]

References[edit]