In each grey cell, place an integer from -8 to -1 or from 1 to 8. Numbers in grey cells must be all different.
In each white cell, place the sum of numbers in two cells it lies between. Numbers in white cells must be all different.
A number in a grey cell can be identical to a number in a white cell.
(Example from WPC 2015 IB)
History of the puzzle
Invented by Whit McMahan (USA) in 2014. First appeared on Whit's Facebook page.
Appearances in the past WPCs
- WPC 2015/Round 10 by Whit McMahan