non-adjacent-robbery.rb

D = false
def even_sum(array)
  result = 0
  array.each_with_index do |elem, i|
    result += elem if i % 2 == 0
  end
  result
end

def odd_sum(array)
  result = 0
  array.each_with_index do |elem, i|
    result += elem if i % 2 == 1
  end
  result
end

def rob(array)
  p 'rob(' + array.inspect + ')' if D
  return 0 if array.length == 0
  return array[0] if array.length == 1
  a = array[0]
  b = array[1]
  c = array[2] || 0
  d = array[3] || 0

  # vals = {a_c: a+c, b_d: b+d, a_d: a+d}

  # p 'vals: ' + vals.inspect if D

  # max = vals.max_by { |k,v| v }

  # p 'max: ' + max.inspect if D

  # if max[0] == :a_c || max[0] == :a_d
  #   i = 0
  # else
  #   i = 1
  # end
  if even_sum(array) > odd_sum(array)
    i = 0
  else
    if array.length > 3
      if array[3] > array[2] + array[1]
        i = 0
      else
        i = 1
      end
    else
      i = 1
    end
  end
  # if array.length == 2
  #   p 'length == 2' if D
  #   if array[0] > array[1]
  #     i = 0
  #   else
  #     i = 1
  #   end
  # elsif array.length == 3
  #   p 'length == 2' if D
  #   if array[0] + array[2] > array[1]
  #     i = 0
  #   else
  #     i = 1
  #   end
  # elsif array.length == 4
  #   p 'length == 3' if D
  #   if array[0] + array[2] > array[1] + array[3]
  #     i = 0
  #   else
  #     i = 1
  #   end
  # elsif array.length > 4
  #   p 'length > 4' if D
  #   if array[0] + array[2] + array[4] > array[1] + array[3]
  #     i = 0
  #   else
  #     i = 1
  #   end
  # end

  p 'i: ' + i.to_s if D

  result = array[i]

  p 'result: ' + result.to_s if D

  if i > 0
    prev_i = i - 1
  else
    prev_i = i
  end

  # p 'prev_i: ' + prev_i.to_s if D

  if i < array.length - 1
    next_i = i + 1
  else
    next_i = i
  end

  # p 'next_i: ' + next_i.to_s if D

  array.slice!(prev_i..next_i)
  result + rob(array)
end

def assert(condition)
  raise 'falsey' unless condition
end

p rob([6,4,2,1,3,5]) if D
assert(true) unless D
assert(rob([1]) == 1) unless D
assert(rob([1,2]) == 2) unless D
assert(rob([2,1]) == 2) unless D
assert(rob([1,2,3]) == 4) unless D
assert(rob([3,2,1]) == 4) unless D
assert(rob([2,3,2]) == 4) unless D
assert(rob([3,2,3]) == 6) unless D
assert(rob([1,2,3,4]) == 6) unless D
assert(rob([4,3,2,1]) == 6) unless D
assert(rob([1,3,4,2]) == 5) unless D
assert(rob([4,1,2,3]) == 7) unless D
assert(rob([1,2,3,4,5]) == 9) unless D
assert(rob([5,4,3,2,1]) == 9) unless D
assert(rob([1,4,5,3,2]) == 8) unless D
assert(rob([5,3,1,2,4]) == 10) unless D
assert(rob([1,2,3,4,5,6]) == 12) unless D
assert(rob([6,5,4,3,2,1]) == 12) unless D
assert(rob([6,4,2,1,3,5]) == 13) unless D
assert(rob([1,3,5,6,4,2]) == 11) unless D

assert(rob([1,2,3,4,5,6,7]) == 16) unless D
assert(rob([7,6,5,4,3,2,1]) == 16) unless D
assert(rob([6,4,2,1,3,5,7]) == 18) unless D
assert(rob([1,3,5,7,6,4,2]) == 14) unless D

# assert(rob([1,3,5,6,4,2]) == 11) unless D
puts 'ok' unless D