stevencch99

def primeString(s)
  (s + s).index(s, 1) == s.size
end

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function primeString(s) {
  return (s + s).indexOf(s, 1) == s.length;
}

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function primeString(s) {
  // 將字串重複的部份切成一個規律的陣列
  let spArr = s.split(s[0]);
  // 切掉不要的頭部空元素
  spArr.shift();
  // 宣告 不重複計數器
  let falseCount = 0;
  //  將各個元素和它們出現的次數存成 key-value pair
  let tCounter = {};
  spArr.forEach(x => { tCounter[x] = (tCounter[x] || 0) + 1; });

stevencch99

[CodeWars] 解題：Simple Fun #116: Prime String

This is a 6kyu Kata on CodeWars (https://www.codewars.com), that I used to practice programing skill.

Codewars 是我在走跳的刷題網站，相關介紹請參考 透過 codewars 修練 Swift 解題技巧 by @彼得潘的 iOS App Neverland

上面的題目分為最簡單的 8 kyu 到最難的 1 kyu，送交答案之後就可以看到其他 Code Warriors 不同的解法和各種奇思妙想。

今天來談談這讓我徹夜難眠的一題：難度 6 kyu 的

stevencch99

class Greeter
  attr_reader :greeting

  def initialize(greeting)
    @greeting = greeting
  end

  def greet(subject)
    "#{greeting}, #{subject}!"
  end

stevencch99

to_camel = :capitalize.to_proc
add_header = -> val { "Title: " + val }
strip_space = :strip.to_proc

format_as_title = add_header << to_camel << strip_space


format_as_title[" \thello world\n"]
# "Title: Hello world"

stevencch99

double_then_square = square << double
double_then_square[2] # => 16

square_then_double = square >> double
square_then_double[2] # => 8
(square >> double)[2] # => 8

stevencch99

class Greeter
  attr_reader :greeting

  def initialize(greeting)
    @greeting = greeting
  end

  def greet(subject)
    "#{greeting}, #{subject}!"
  end

stevencch99

double_p = proc { |number| return number * 2}
double_p[2] # => LocalJumpError (unexpected return)

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double = lambda { |number| number * 2 }
double = -> (number) { return number * 2 }
double[2] # => 4
double[2, 3] # => ArgumentError (wrong number of arguments (given 2, expected 1))