MathDB

In a

3

3

table, by a

k

-worm, we mean a path of different cells

(S_1,S_2,...,S_k)

such that each two consecutive cells have one side in common. The

k

-worm at each steep can go one cell forward and turn to the

(S,S_1,...,S_{k-1})

S

is an unfilled cell which is adjacent (has one side in common) with

S_1

. Find the maximum number of

k

such that there is a

k

-worm

(S_1,...,S_k)

such that after finitly many steps can be turned to

(S_k,...,S_1)

Problem Statement