ruby-on-rails - 数组不返回最频繁的值

Question

def most_common_letter(string)
  letter = nil
  final_letter = nil
  letter_count = nil
  idx1 = 0
  idx2 = 0
  count = 0
  while idx1 < string.length
    letter = string[idx1]
    while idx2 < string.length
      if letter == string[idx2]
        count += 1
      end
    idx2 += 1
    end
    if (letter_count == nil) || (count > letter_count)
      letter_count = count
      final_letter = letter
    end
  idx1 += 1
  end
  arr = []
  arr.push(final_letter)
  arr.push(letter_count)
  return arr
end

puts(most_common_letter("abbab") == ["b", 3])
#should be true

不断获取 [a,2] 这让我相信它只是在执行部分代码，而在我看来代码应该在每次出现更频繁的字母时重置最终字母的值和字母计数。我哪里出错了？

Answer 1

这种类型的问题通常使用计数哈希:

def most_frequent_letter(str)
  str.each_char.with_object(Hash.new(0)) { |c,h| h[c] += 1 }.max_by(&:last)
end

most_frequent_letter("bananas are so-so")
  #=> ["a",4]

步骤:

h = "bananas are so-so".each_char.with_object(Hash.new(0)) { |c,h| h[c] += 1 }
  #=> {"b"=>1, "a"=>4, "n"=>2, "s"=>3, " "=>2, "r"=>1, "e"=>1, "o"=>2, "-"=>1}
h.max_by(&:last) 
  #=> ["a",4]