Editorial for COCI '08 Regional #3 Cijevi
Remember to use this editorial only when stuck, and not to copy-paste code from it. Please be respectful to the problem author and editorialist.
Submitting an official solution before solving the problem yourself is a bannable offence.
Submitting an official solution before solving the problem yourself is a bannable offence.
First write four auxiliary functions left(r,c), right(r,c), up(r,c) and down(r,c) telling us if gas can flow in each direction from empty cell . For example, the function
left(r,c) can look like this:
return true if Map(r,s-1) = '+' or Map(r,s-1) = '-' or Map(r,s-1) = '1' or Map(r,s-1) = '2'The task can be solved in one pass through the map. For every empty cell , we run the following checks:
if left(r,c) and right(r,c) and up(r,c) and down(r,c) then output r c '+'
else if left(r,c) and right(r,c) then output r c '-'
else if up(r,c) and down(r,c) then output r c '|'
else if right(r,c) and down(r,c) then output r c '1'
else if right(r,c) and up(r,c) then output r c '2'
else if left(r,c) and up(r,c) then output r c '3'
else if left(r,c) and down(r,c) then output r c '4'
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