JuliaでProject Euler(22) - inamori’s diary

Problem 42

function read_names(path)
    open(path, "r") do fp
        for line in eachline(fp)
            return [ s[2:length(s)-1] for s in split(line, ",") ]
        end
    end
end

function is_square(n)
    return Int(floor(sqrt(n)))^2 == n
end

function is_triangle(n)
    # x^2 + x = 2n
    # x = (-1 + sqrt(1 + 8n)) / 2
    return is_square(1 + 8n)
end

function word_score(word)
    return sum(Int(c)-Int('A')+1 for c in word)
end

function read_words(path)
    open(path, "r") do fp
        for line in eachline(fp)
            return [ replace(s, "\"" => "") for s in split(line, ",") ]
        end
    end
end

function e042(path)
    words = read_words(path)
    return sum(1 for word in words if is_triangle(word_score(word)))
end

path_names = ARGS[1]
println(e042(path_names))

Float64をInt64に変換するとき、わざわざ小数点以下が0の浮動小数点数にしてからでないと変換できない。

replaceの引数は、文字列と文字列ではなく、文字列のPair。古いバージョンだと違うので注意。