Merge pull request #190 from ryanneilparker/master

Add binary insertion sort algorithm

sorting/binary_insertion_sort.rb

@@ -0,0 +1,46 @@
+# Ruby implementation of binary insertion sort algorithm
+
+def binary_search(arr, val, start, stop)
+  while start <= stop
+
+    mid = (start + stop) / 2
+
+    if val == arr[mid] # val is in the middle
+      return mid
+    elsif val > arr[mid] # val is on the right side
+      start = mid + 1
+    else
+      stop = mid - 1 # val is on the left side
+    end
+  end
+
+  start
+end
+
+def binary_insertion_sort(arr)
+  n = arr.size
+
+  (0...n).each do |index|
+    j = index - 1
+    selected = arr[index]
+
+    # find location where selected value should be inserted
+    location = binary_search(arr, selected, 0, j)
+
+    # move all elements after location to make space
+    while j >= location
+      arr[j + 1] = arr[j]
+      j -= 1
+      arr[j + 1] = selected
+    end
+  end
+
+  arr
+end
+
+if $0 == __FILE__
+  puts 'Enter a list of numbers separated by space'
+
+  list = gets.split.map(&:to_i)
+  p binary_insertion_sort(list)
+end

sorting/binary_insertion_sort_test.rb

@@ -0,0 +1,11 @@
+require 'minitest/autorun'
+require_relative './sort_tests'
+require_relative './binary_insertion_sort'
+
+class TestBinaryInsertionSort < Minitest::Test
+  include SortTests
+
+  def sort(input)
+    binary_insertion_sort(input)
+  end
+end