Waterline
(Published today, 11:15 by varepsilon)
Link to SudokuPad: https://sudokupad.app/lhjrrk91ef
Normal Sudoku rules apply: Place the digits 1–9 exactly once in every row, column, and 3×3 box.
Waterline Loop:
Draw a single closed loop through cell centres, moving orthogonally. It must visit every non-5 cell exactly once and must not visit any cell containing a 5.
Along each maximal straight segment of the loop, including the turning cells at both ends, the digits must strictly increase or strictly decrease from one end to the other.
At each turn, the digit must be either a valley (1–4 and lower than both adjacent digits on the loop) or a peak (6–9 and higher than both adjacent digits on the loop).
Normal Sudoku rules apply: Place the digits 1–9 exactly once in every row, column, and 3×3 box.
Waterline Loop:
Draw a single closed loop through cell centres, moving orthogonally. It must visit every non-5 cell exactly once and must not visit any cell containing a 5.
Along each maximal straight segment of the loop, including the turning cells at both ends, the digits must strictly increase or strictly decrease from one end to the other.
At each turn, the digit must be either a valley (1–4 and lower than both adjacent digits on the loop) or a peak (6–9 and higher than both adjacent digits on the loop).
Solution code: Digits in row 4, read from left to right.
Solved by Simon Yuan
