StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
text
Body
copied!<p>You can use <a href="http://www.erlang.org/doc/man/timer.html#tc-1" rel="nofollow">timer</a> module to check speed of execution:</p> <pre><code>{Time, Value} = timer:tc(queen, queen, [N]) </code></pre> <p>Or you can transform you code to escript:</p> <pre><code>#!/usr/bin/env escript -mode(native). %% to fun faster main([NStr]) -> N = list_to_integer(NStr), IJ = [{I, J} || I <- lists:seq(1, N), J <- lists:seq(1, N)], lists:foreach(fun({I, J}) -> put_data(I, J, true) end, IJ), solve(N, 1, [], 0). solve(N, J, Board, Count) when N < J -> print(N, Board), Count + 1; solve(N, J, Board, Count) -> F = fun(I, Cnt) -> case get_data(I, J) of true -> put_data(I, J, false), Cnt2 = solve(N, J+1, [I|Board], Cnt), put_data(I, J, true), Cnt2; false -> Cnt end end, lists:foldl(F, Count, lists:seq(1, N)). put_data(I, J, Bool) -> put({row, I }, Bool), put({add, I+J}, Bool), put({sub, I-J}, Bool). get_data(I, J) -> get({row, I}) andalso get({add, I+J}) andalso get({sub, I-J}). print(N, Board) -> Frame = "+-" ++ string:copies("--", N) ++ "+", io:format("~s~n", [Frame]), lists:foreach(fun(I) -> print_line(N, I) end, Board), io:format("~s~n", [Frame]). print_line(N, I) -> F = fun(X, S) when X == I -> "Q " ++ S; (_, S) -> ". " ++ S end, Line = lists:foldl(F, "", lists:seq(1, N)), io:format("| ~s|~n", [Line]). </code></pre> <p>and make it executable from linux shell:</p> <pre><code>chmod +x queue </code></pre> <p>And then run it from linux shell with command <code>./queue</code> or <code>time ./queue</code></p>

Querying!

Guidance

An individual column

Larger individual text columns get their own page to allow for proper reading.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload