Rail Pool
Rules[edit]
Draw a non-intersecting loop through the centers of all cells. Clues represent all of the different lengths of the straight line segments that are at least partially contained within the region. Each number within a region must be represented by at least one line segment. Each ? represents a positive integer, and numbers cannot repeat within a region.
(Rules and Example from WPC 2022 IB)
History of the puzzle[edit]
Invented by Martin Ender (Germany). The first puzzles were posted on Discord, then later ported to Martin's blog. [1]
The name "Rail Pool" was originally conceived by reversing the letters of each word of "Liar Loop", another genre involving regions and loops. It is also thematic, as clues indicate a "pool" of lengths the loop must sample from when traversing each region.
Variants[edit]
Forgetful[edit]
Draw a non-intersecting loop through the centers of all cells, except for exactly one in each region. Clues represent all of the different lengths of the straight line segments that are at least partially contained within the region. Each number within a region must be represented by at least one line segment. Each ? represents a positive integer, and numbers cannot repeat within a region.
(Rules and Example from WPC 2022 IB)
Appearances in the past WPCs[edit]
- WPC 2023/Round 13 by David Altizio
- WPC 2022/Round 3 by Martin Ender
- WPC 2022/Round 8 by Martin Ender
- WPC 2022/Round 13 (Forgetful) by Martin Ender
- WPC 2022/Round 17 by Martin Ender