binary_search.rb

# Place your solutions here
# Implement a method named binary_search
def binary_search(target, arr)
  s = 0
  e = arr.length - 1
  until s < e
    m = (s + e) / 2
    # found target
    if target == arr[m]
      return m
    # target is on left side of the midpoint (set ending point to midpoint)
    elsif target < arr[m]
      e = m - 1
    # target is on right side of the midpoint (set starting point to midpoint)
    else
      s = m + 1
    end
  end
  return nil
end

p binary_search(201, (1..200).to_a)