bin_search.rb

# coding: utf-8

def bin_search(array, search)
  lowerbound = 0
  upperbound = array.size - 1
  while (lowerbound <= upperbound)
    middle = (lowerbound + upperbound) / 2
    return middle if (search == array[middle])
    if (search < array[middle])
      upperbound = middle - 1
    else
      lowerbound = middle + 1
    end
  end
  return -1
end