Created
January 3, 2014 10:47
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「回文基数」をErlangとRubyで(横へな17参考) ref: http://qiita.com/pazworld/items/3b936680585b60ad82c3
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-module(sheh). | |
-compile(export_all). | |
solve(Data) -> bases(list_to_integer(Data)). | |
bases(1) -> "-"; | |
bases(X) -> to_s(lists:filter(fun(Base) -> | |
X =:= rev(X, Base, 0) end, lists:seq(2, X - 1))). | |
to_s([]) -> "-"; | |
to_s(Bs) -> string:join([integer_to_list(X) || X <- Bs], ","). | |
rev(0, _, Acc) -> Acc; | |
rev(X, Base, Acc) -> rev(X div Base, Base, Acc * Base + (X rem Base)). | |
test(Data, Expected) -> test(Data, solve(Data), Expected). | |
test(Data, Result, Expected) -> io:fwrite("~s: ~s -> ~s~n", | |
[case Result =:= Expected of true -> ok; false -> ng end, Data, Result]). | |
tests() -> | |
test("17301", "5,38,100,218,236,5766,17300"), %0 | |
test("2", "-"), %1 | |
test("1", "-"), %2 | |
test("3", "2"), %3 | |
test("4", "3"), %4 | |
test("5", "2,4"), %5 | |
test("6", "5"), %6 | |
test("10", "3,4,9"), %7 | |
test("101", "10,100"), %8 | |
test("1001", "10,25,76,90,142,1000"), %9 | |
test("10001", "10,24,30,42,80,100,136,10000"), %10 | |
test("1212", "22,100,201,302,403,605,1211"), %11 | |
test("123412", "62,100,205,215,30852,61705,123411"), %12 | |
test("5179", "5178"), %13 | |
test("4919", "4918"), %14 | |
test("5791", "5790"), %15 | |
test("5498", "2748,5497"), %16 | |
test("453", "150,452"), %17 | |
test("134", "66,133"), %18 | |
test("8489", "27,652,8488"), %19 | |
test("1234", "22,616,1233"), %20 | |
test("5497", "41,238,5496"), %21 | |
test("4763", "19,35,432,4762"), %22 | |
test("3974", "17,27,1986,3973"), %23 | |
test("3521", "44,55,502,3520"), %24 | |
test("5513", "20,38,53,148,5512"), %25 | |
test("8042", "23,29,60,4020,8041"), %26 | |
test("7442", "37,60,121,3720,7441"), %27 | |
test("4857", "25,1618,4856"), %28 | |
test("22843", "49,69,91,141,430,22842"), %29 | |
test("194823", "84,121,21646,64940,194822"), %30 | |
test("435697", "160,169,235,626,1822,435696"), %31 | |
test("142", "3,7,70,141"), %32 | |
test("886", "5,14,442,885"), %33 | |
test("3102", "7,65,93,140,281,516,1033,1550,3101"), %34 | |
test("17326", "11,28,99,105,8662,17325"), %35 | |
test("32982", "13,72,238,477,716,1433,5496,10993,16490,32981"), %36 | |
test("36", "5,8,11,17,35"), %37 | |
test("37", "6,36"), %38 | |
test("251", "8,250"), %39 | |
test("252", "5,10,17,20,27,35,41,62,83,125,251"), %40 | |
test("253", "12,14,22,252"), %41 | |
test("6643", "2,3,9,81,90,510,948,6642"), %42 | |
test("5040", "71,79,83,89,104,111,119,125,139,143,167,179,209,239,251,279,314,335,359,419,503,559,629,719,839,1007,1259,1679,2519,5039"), %43 | |
test("9240", "23,38,62,104,109,119,131,139,153,164,167,209,219,230,263,279,307,329,384,419,439,461,615,659,769,839,923,1154,1319,1539,1847,2309,3079,4619,9239"). %44 |
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def solve(data) | |
x = data.to_i | |
x < 3 ? "-" : (2...x).select { |b| x == rev(x, b, 0) } * "," | |
end | |
def rev(x, base, acc) | |
x == 0 ? acc : rev(x.div(base), base, acc * base + (x % base)) | |
end |
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