08 - Mexican Wave

Don't say so much, just coding...

Instruction

In this simple Kata your task is to create a function that turns a string into a Mexican Wave. You will be passed a string and you must return that string in an array where an uppercase letter is a person standing up.

Rules:

1. The input string will always be lower case but maybe empty.
2. If the character in the string is whitespace then pass over it as if it was an empty seat

Examples:

  wave("hello") => ["Hello", "hEllo", "heLlo", "helLo", "hellO"]

Ruby

Init

  def wave(str)
    # ...
  end

Sample Testing

  result = ["Hello", "hEllo", "heLlo", "helLo", "hellO"];
  Test.assertDeepEquals(wave("hello"),result, "Should return: '"+result+"'");
  
  result = ["Codewars", "cOdewars", "coDewars", "codEwars", "codeWars", "codewArs", "codewaRs", "codewarS"];
  Test.assertDeepEquals(wave("codewars"), result, "Should return: '"+result+"'");
  
  result = [];
  Test.assertDeepEquals(wave(""), result, "Should return: '"+result+"'");
  
  result = ["Two words", "tWo words", "twO words", "two Words", "two wOrds", "two woRds", "two worDs", "two wordS"];
  Test.assertDeepEquals(wave("two words"), result, "Should return: '"+result+"'");
  
  result = [" Gap ", " gAp ", " gaP "];
  Test.assertDeepEquals(wave(" gap "), result, "Should return: '"+result+"'");

Javascript

Init

  function wave(str){
    // Code here
  }

Sample Testing

  result = ["Hello", "hEllo", "heLlo", "helLo", "hellO"];
  Test.assertDeepEquals(wave("hello"),result, "Should return: '"+result+"'");
  
  result = ["Codewars", "cOdewars", "coDewars", "codEwars", "codeWars", "codewArs", "codewaRs", "codewarS"];
  Test.assertDeepEquals(wave("codewars"), result, "Should return: '"+result+"'");
  
  result = [];
  Test.assertDeepEquals(wave(""), result, "Should return: '"+result+"'");
  
  result = ["Two words", "tWo words", "twO words", "two Words", "two wOrds", "two woRds", "two worDs", "two wordS"];
  Test.assertDeepEquals(wave("two words"), result, "Should return: '"+result+"'");
  
  result = [" Gap ", " gAp ", " gaP "];
  Test.assertDeepEquals(wave(" gap "), result, "Should return: '"+result+"'");

Thinking

想法(1): 將所有字都先轉為小寫，在透過跑迴圈來看第幾個字為大寫 + 其餘小寫
想法(2): 複製原本傳入的值出來後，再將大寫的字 assign 回複製出來的值

圖片來源：Unsplash C D-X

Hint & Reference

• Ruby
  • Ruby - apidock each_with_index
  • Ruby - apidock downcase
  • Ruby - apidock upcase
• JavaScript
  • JS - MDN Array.prototype.slice
  • JS - MDN String.prototype.toUpperCase

Solution

Ruby

  # Solution 1
  def wave(str)
    result = []
    chars = str.downcase.chars
    chars.each_with_index do |char, index|
      next if char == " "
      result << str[0...index] + char.upcase + str[index+1..-1]
    end
    result
  end
  
  # Solution 2
  def wave(str)
    result = []
    str.size.times do |index|
      next if str[index] == ' '
      result << str.dup
      result[-1][index] = result[-1][index].upcase
    end
    result
  end

Javascript

  // Solution 1
  function wave(str){
    var result = [];
    for (i = 0; i < str.length; i++) {
      if (str[i] != ' ') 
      result.push(str.slice(0, i) + str[i].toUpperCase() + str.slice(i + 1))
    }
    return result;
  }