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for university I have to implement an algorithm which creates all possibile magic squares for a given edge length and a specific sum. For n=3 the algorithm is working as expected. But when generating all magic squares for n=4 after a while I ran out of memory. This problem was already mentioned in the task description. I already tried to optimize the a code but it is still not working as it should. So I hope someone can give me some advice. My basic idea is: First I generate all possible rows which I can use with the given numbers and then I'm trying to combine these in a way that the restrictions of a magic square are fullfilled. This happens via backtracking. I think the problem is the function makeRows which consumes too much memory after while for storing all the rows. If you need some more explanation of the code I can give! magicSquare(N, Value) -> Squares = buildSquare(N, makeRows(N, N*N, Value, N)), io:fwrite("Squares ready"), io:fwrite("~n"), Result = lists:filter(fun(X) -> testsquare(X, N, Value) end, Squares), io:write(length(Result)), Result. buildSquare(0, _) -> [[]]; buildSquare(Rows, AvailableRows) -> [ [X|L] || L <- buildSquare(Rows-1, AvailableRows), X <- AvailableRows, onlyUniqueNumbers(lists:flatten([X|L]))]. onlyUniqueNumbers(List) -> erlang:length(List) == sets:size(sets:from_list(List)). %produces all possible rows with a dimension of Fields and the Numbers from 1 to Numbers and the right sum for each row makeRows(0,_,_,_) -> [[]]; makeRows(Fields, Numbers, Value, TargetLength) -> [ [X|L] || X <- makeRows(Fields-1, Numbers, Value, TargetLength), L <- lists:seq(1,Numbers), checkRow([X|L], TargetLength, Value)]. checkRow(Row, Length, Value) when length(Row) < Length -> true; checkRow(Row, Length, Value) -> Sum = lists:sum(Row), if Sum == Value -> true; true -> false end. testsquare(Square, N, Value) ->

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