Sorting in Ruby

sort-ruby.rb

#My implementation of sorting algorithms in Ruby

#insertion sort

def sort_insert(a)
  index = 1
  while index < a.length
    value = a[index]  
    a[0...index].each_with_index do |sorted_value, i|
      if value < sorted_value
        a.slice!(index)
        a.insert(i, value)
        break
      end
    end
   index += 1
  end
  a
end

#selection sort

def sort(a)
  n = a.size - 1
  n.times do |i|
    index = i
    (i + 1).upto(n) { |j| index = j if a[j] < a[index] }
    a[i], a[index] = a[index], a[i] unless index == i
  end
  a
end

#merge sort

def mergesort(list)
  return list if list.size == 1
  
  length = list.length/2 - 1
  left = mergesort(list[0..length])
  right = mergesort(list[length+1..-1])
  
  merge(left,right)
end

def merge(left,right)
  lindex = rindex = 0
  out = []

  loop do
    if left[lindex] == nil
      out += right[rindex..-1]
      break 
    elsif right[rindex] == nil
      out += left[lindex..-1]
      break 
    end 
   
    if right[rindex] < left[lindex] 
      out << right[rindex]
      rindex += 1
    else 
      out << left[lindex]
      lindex += 1
    end
  end
  out
end

#bubble sort

def bubble_sort(a)
  length = a.size - 1
  loop do 
    switch = false
    1.upto(length) do  |i|
      if a[i] < a[i-1]
      	a[i], a[i-1] = a[i-1], a[i] 
        switch = true
      end
    end
    return a unless switch 
  end
end