anagram_string.rb

# Check whether two strings are anagram of each other

def merge_sort(ar)
  return ar if ar.length == 1

  mid = ar.length / 2
  left = ar[0, mid]
  right = ar[mid, ar.length - 1]
  first_half = merge_sort(left)
  second_half = merge_sort(right)
  merge(first_half, second_half)
end

def merge(ar1, ar2)
  sorted_array = []
  i = 0
  j = 0
  while i < ar1.length && j < ar2.length
    if ar1[i] <= ar2[j]
      sorted_array << ar1[i]
      i += 1
    else
      sorted_array << ar2[j]
      j += 1
    end
  end

  while i < ar1.length
    sorted_array << ar1[i]
    i += 1
  end

  while j < ar2.length
    sorted_array << ar2[j]
    j += 1
  end
  sorted_array
end

# using 2 arrays
def is_anagram?(str1, str2)
  ar1 = Array.new(256, 0)
  ar2 = Array.new(256, 0)
  str1.each_char do |char|
    ar1[char.ord] += 1
  end

  str2.each_char do |char|
    ar2[char.ord] += 1
  end

  (0..255).each do |e|
    return false if ar1[e] != ar2[e]
  end
  true
end

# using single array
def is_anagram2?(str1, str2)
  ar = Array.new(256, 0)
  str1.each_char do |char|
    ar[char.ord] += 1
  end

  str2.each_char do |char|
    ar[char.ord] -= 1
  end
  puts ar.to_s

  (0..255).each do |e|
    return false if ar[e] != 0
  end
  true
end

def is_anagram1?(str1, str2)
  return false if str1.length != str2.length

  merge_sort(str1.split('')) == merge_sort(str2.split(''))
end

# puts is_anagram?('test', 'ttew')
# puts is_anagram?('abcd', 'dabc')

puts is_anagram2?('test', 'ttew')
puts is_anagram2?('abcd', 'dabc')