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Facebook task solution http://habrahabr.ru/post/210796/
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-module(facebook). | |
-export([square/1, print_square/1]). | |
square(N)->square(1, N). | |
square(Start, 1)->[[Start]]; | |
square(Start, 2)->[[Start, Start+1], [Start+3, Start+2]]; | |
square(Start, N)-> | |
TopRight = Start+N-1, | |
[lists:seq(Start, TopRight)]++ | |
extend(square(TopRight+3*N-3, N-2), TopRight+3*N-4, TopRight+1, [])++ | |
[lists:reverse(lists:seq(TopRight+N-1, TopRight+2*N-2))]. | |
extend([H|T], Left, Right, Acc)-> | |
extend(T, Left-1, Right+1, [[Left]++H++[Right]|Acc]); | |
extend([], _, _, Acc)->lists:reverse(Acc). | |
print_square(N)-> | |
lists:foreach(fun(Row)->io:format("~w~n", [Row]) end, square(N)). |
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