complete w/ quick sort

README.md

@@ -1,2 +1,5 @@
 # assignment_sort
 Insertion and Merge Sort assignment
+
+
+Richard Bell

bubble.rb

@@ -0,0 +1,31 @@
+# implementation of bubble sort on an array
+class BubbleSort
+  def initialize(input_array)
+    @input = input_array
+    @flipping = true
+  end
+
+  def sort
+    while @flipping
+      @flipping = false
+      (@input.length - 1).times do |i|
+        flip(i) if @input[i + 1] < @input[i]
+      end
+    end
+    @input
+  end
+
+  private
+
+  def flip(index)
+    @flipping = true
+    @input[index], @input[index + 1] = @input[index + 1], @input[index]
+  end
+end
+
+
+# test code
+if __FILE__ == $PROGRAM_NAME
+  bub = BubbleSort.new([2, 3, 1,5,3,6,-4,2,8,9,14])
+  puts bub.sort.inspect
+end

insertion.rb

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+# implementation of insertion sort on an array
+class InsertionSort
+  def initialize(input_array)
+    @input = input_array
+  end
+
+  def sort
+    (@input.length - 1).times do |i|
+      insert(@input, i, @input[i + 1])
+    end
+
+    @input
+  end
+
+  private
+
+  def insert(array, right_index, value)
+    # value is the value of array[right_index + 1]
+    # right_index is the furthest right sorted element
+
+    # Step through sorted elements right to left.
+    # As long as your value is less than the element
+    # at array[i] and you still have elements
+    i = right_index
+    while (i >= 0 && array[i] > value)
+      # copy the element
+      array[i + 1] = array[i]
+      i -= 1
+    end
+
+    # insert the actual element
+    array[i + 1] = value
+  end
+end
+
+
+# test code
+if __FILE__ == $PROGRAM_NAME
+  ins = InsertionSort.new([2, 3, 1,7,4,5,2,9,0,-5,3])
+  puts ins.sort.inspect
+end

merge.rb

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+# implementation of merge sort on an array
+class MergeSort
+  def initialize(input_array)
+    @input = input_array
+  end
+
+  def sort
+    merge_sort(@input)
+  end
+
+  private
+
+  def merge_sort(array)
+    return array if array.length == 1
+    middle = (array.length / 2).floor - 1
+    left = merge_sort(array[0..middle])
+    right = merge_sort(array[(middle + 1)..-1])
+    merge(left, right)
+  end
+
+  def merge(array_left, array_right)
+    merged = []
+    until array_left.empty? || array_right.empty?
+      array_left[0] < array_right[0] ? merged << array_left.shift : merged << array_right.shift
+    end
+    merged += array_right if array_left.empty?
+    merged += array_left if array_right.empty?
+    merged
+  end
+end
+
+# test code
+if __FILE__ == $PROGRAM_NAME
+  merge = MergeSort.new([2, 3, 1, 5, 7, -5, 4, 14, 1, 0, 17])
+  puts merge.sort.inspect
+end

quicksort.rb

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+# implementation of quick sort on an array
+class QuickSort
+  def initialize(input_array)
+    @input = input_array
+  end
+
+  def sort
+    quick_sort(@input)
+  end
+
+  private
+
+  def quick_sort(array)
+    return array if array.length <= 1
+    pivot = array.delete_at(rand(array.size))
+    left = []
+    right = []
+    array.each do |e|
+      e < pivot ? left << e : right << e
+    end
+    left << pivot
+    quick_sort(left) + quick_sort(right)
+  end
+end
+
+# test code
+if __FILE__ == $PROGRAM_NAME
+  quick = QuickSort.new([2, 4, 3, 1, 5, -7, 0, 15, 4, 8, 12])
+  puts quick.sort.inspect
+end