Place a number from 1 to X (integers only) into each circled cell so that the numbers along each line are all different. (X is the number of cells along the longest line.) The numbers inside the grid indicate the sum of the three numbers in the adjacent circled cells. Some cells may already be filled in for you.
(Rules and example from PGP IB)
History of the puzzle
Invented by Riad Khanmagomedov (Russia). First appeared on 2009 edition of Riad's April Contest. The name is possibly from contraction of "Triangular Grid."
Appearances in the past WPCs
- WPC 2019/Round 7 by Ulrich Voigt