10, Common Lisp - rextester

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;gnu clisp  2.49.60
#|
Для каждого блюда известен набор продуктов, необходимый для его приготовления, и количество каждого продукта. 
Дан список продуктов, имеющихся в наличии: какой продукт и сколько.
Написать функцию, формирующую возможное меню. Учитывать, что суммарное количество продуктов в меню не может превышать имеющееся.
|#

(defun ingredient-is-available-and-sufficient (available-ingredients required-ingredient)
    (let (answer))
    (setf answer nil)
    
     (loop for a in available-ingredients
             if (string= (first a) (first required-ingredient))
                  if (>= (second a) (second required-ingredient))
                      do (setf answer t) and
                       return t
                  else 
                       do (setf answer nil) and
                      return nil
    )
    answer
  )

(defun required-ingredients-are-available-and-sufficient (available needed)
    (let (answer))
    (setf answer t)
    (loop for n in needed
         if (not (ingredient-is-available-and-sufficient available n))
          do (setf answer nil) and
          return nil
          
     )
    answer
    )

(defun reserve-ingredients (available-ingredients required-ingredients)
    
    (loop for r in required-ingredients
          do (loop for a in available-ingredients
               if (string= (first a) (first r))
                do (setf (second a) (- (second a) (second r))) and
                return nil
           )
     )
    available-ingredients
    )

(defun make-menu (available-ingredients dishes) 
    (let (menu))
    (setf menu (list))
    (loop for d in dishes
         if (required-ingredients-are-available-and-sufficient available-ingredients (second d))
          do (setf available-ingredients (reserve-ingredients available-ingredients (second d))) and
          do (setf menu (nconc menu (list d)))
     )
    menu
    )

(let (available-ingredients))
(setf available-ingredients '(("carrot" 2000) ("onion" 1300) ("potato" 5000) ("chicken" 800) ("zuccini" 500) ("sausage" 600) ("cheese" 500)))

(let (dishes))
(setf dishes '(("roasted potato" (("potato" 1300) ("onion" 400))) ("zuccini slice" (("zuccini" 400) ("cheese" 500) ("onion" 300) )) 
                                                                  ("baked potato" (("potato" 2000) ("sausage" 500) ("cheese" 400)))  ))

(print ( make-menu  available-ingredients dishes));(second (first dishes))))

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Absolute running time: 0.16 sec, cpu time: 0.02 sec, memory peak: 9 Mb, absolute service time: 0,29 sec