Numberlink facts for kids
Numberlink is a type of logic puzzle involving finding paths to connect numbers in a grid.
Rules
The player has to pair up all the matching numbers on the grid with single continuous lines (or paths). The lines cannot branch off or cross over each other, and the numbers have to fall at the end of each line (i.e., not in the middle).
It is considered that a problem is well-designed only if it has a unique solution and all the cells in the grid are filled, although some Numberlink designers do not stipulate this.
Computational complexity
As a computational problem, finding a solution to a given Numberlink puzzle is NP-complete. NP-completeness is maintained even if "zig-zag" paths are allowed. Informally, this means paths may have "unnecessary bends" in them (see the reference for a more technical explanation).
