Czech republic

 

 

 

 

 

 

Fig. 6 Another picture of Fig. 5 

 

Fig. 7 Solution of the puzzle Cities 

 

Before we start to deal with the others puzzles let us 

briefly remind the well-known Breadth-First-Search 

algorithm. We describe it using Czech meta-

language (see the section 2.1) and as an edge 

colouring process. We also introduce the definition 

of the Breadth-First-Search Tree, appropriate 

theorem and statement discussed thereinafter in this 

paper.  

begin 

initially all vertices and edges of 

the given connected undirected graph 

G, with n vertices and m edges, are 

uncoloured. Choose any single vertex, 

insert it into FIFO, colour it blue 

and search it.