Binary Search - Complete

binary_search.rb

def binary_search(n, arr)
  middle = arr.length / 2
  i = 0
  j = arr.length - 1

  while i < j
    if arr[middle] == n
      return true
    elsif arr[middle] < n
      i = middle + 1
      middle = i + j / 2
    else
      j = middle - 1
      middle = i + j / 2
    end
  end
  false
end 

There's a bug. middle = i + j / 2 should be middle = (i + j) / 2, with the parenthesis

And also, how about moving the middle = ... to the top like below:

def binary_search(n, arr)
  i = 0
  j = arr.length - 1

  while i < j
    middle = (j + i) / 2
    if arr[middle] == n
      return true
    elsif arr[middle] < n
      i = middle + 1
    else
      j = middle - 1
    end
  end
  false
end

This is incorrect as well.

This is a working solution + simple tests

def binary_search(n, array)
        i = 0
        final_index = array.size - 1

        while i <= final_index
            # calculate middle
            middle = (i + final_index)/2
            if array[middle] == n
                return true
            elsif array[middle] < n
                i = middle + 1
            # when array[middle] > n
            else
                final_index = middle - 1
            end
        end
        false
    end

    # testing for finding all values
    array = [1,2,6,7,8,44,56]
    results = []
    i = 0
    while i < array.size
        results << binary_search(array[i], array)
        i = i + 1
    end

    # final test, testing for a non-available value
    results << binary_search(69, array)
    
    # we should get 7 true consequentively and a false at the end
    results == [true, true, true, true, true, true, true, false]