;;Autor: Paola Andrea Domínguez Vélez
;;Fecha: 8/08/2020
;;Contrato: buscar-mayor: lista de numeros--> numero
;;Proposito: Tomar una lista de 5 números y retornar el mayor de estos.
;;Ejemplo
;;(buscar-mayor (cons 3 (cons 4 (cons 5 (cons 6 (cons 1 empty)))))) 6)
;;(buscar-mayor (cons 9 (cons 10 (cons 50 (cons 3 (cons 5 empty)))))) 50)


(define (buscar-mayor lstnum)
  (cond
    [(not (cons? lstnum)) (error "Debe ingresarse una lista de números")]
    [(and (> (first lstnum) (first (rest lstnum)))
          (> (first lstnum) (first (rest (rest lstnum))))
          (> (first lstnum) (first (rest (rest (rest lstnum)))))
          (> (first lstnum) (first (rest (rest (rest (rest lstnum))))))
          ) (first lstnum)]

    [(and (> (first (rest lstnum)) (first (rest (rest lstnum))))
          (> (first (rest lstnum)) (first (rest (rest (rest lstnum)))))
          (> (first (rest lstnum)) (first (rest (rest (rest (rest lstnum))))))
          ) (first (rest lstnum))]

    [(and  (> (first (rest (rest lstnum))) (first (rest (rest (rest lstnum)))))
           (> (first (rest (rest lstnum))) (first (rest (rest (rest (rest lstnum))))))
           ) (first (rest (rest lstnum)))
             ]

    [(> (first (rest (rest (rest lstnum)))) (first (rest (rest (rest (rest lstnum))))))
     (first (rest (rest (rest lstnum))))
     ]

    [else (first (rest (rest (rest (rest lstnum)))))]
    ))
(check-expect (buscar-mayor (cons 3 (cons 4 (cons 5 (cons 6 (cons 1 empty)))))) 6)
(check-expect (buscar-mayor (cons 9 (cons 10 (cons 50 (cons 3 (cons 5 empty)))))) 50)
(check-expect (buscar-mayor (cons 10 (cons 20 (cons 40 (cons 60 (cons 3 empty)))))) 60)