Chaos

Rules

Place digits from 1 to 4 into some cells. Each row and column must contain every digit exactly once. Numbers outside the grid give the sum of all digits which are between the two empty cells in the corresponding row or column.

(Rules and example from WPC 2015 IB)

History of the puzzle

Invented by Olga Leontieva (Russia) and first appeared in 2008 Russian Puzzle Championship.

Appearances in the past WPCs

• WPC 2015/Round 3 by Andrey Bogdanov